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I quite like the new design. I think the need for them to look like actual "tabs" like in a folder is overblown. Let's drop the skeuomorphism.

The customizability in Firefox is great, but the example in the link is... well, to each their own.

Linking two related UI elements isn't a "skeuomorph". It is an element of design. A skeuomorph is when you try to make a UI look like a physical object: adding paper grain to the background of a word processor, or making a time app look like a stopwatch.
More generally, a skeuomorph is when a derivative uses design elements for decoration that were functionally necessary in the original. Paper grain in the background of a word processor is one example of a skeuomorph — but so are spokes on hubcaps, electric lights shaped like candles and the shutter sound your phone plays when it takes a picture.
> A skeuomorph is when you try to make a UI look like a physical object

Agreed, and the linked article specifically themes their tabs to look like a file folder, with a reminiscent color and rounded corners.

The very concept of a tab that contains related information in it is a replication of the physical tabbed file folder.

It's pretty much this: https://imgur.com/a/u2WgESW

And that is largely a hold over from the concept of a physical desktop in an office. See: https://onezero.medium.com/the-document-metaphor-desktop-gui...

It'd be nice for some new concepts to be introduced and refined.

IMO this is more about affordance than about skeuomorphism. The traditional tab strip UI is already an abstraction, because it has only two levels of depth (instead of each tab having a different depth like physical tabs) and you don’t see the stack of individual edges of each tab page. (There were skeuomorphic versions that actually did this.) The new Firefox design is lacking any clear affordance that would connect the tab button to the respective tab contents.
Tab-look isn't skeuomorphism, the way it's used most places in computer UI—it indicates to the user which parts of the UI are associated with the tab, and so may be expected to change when the tab is switched.
Which is not the case of the UI element right under the tab bar ... because it's the toolbar / address bar. In earlier versions of Firefox, tabs used to be located under the toolbars hence they made sense as tabs.

Only Safari kept this UX. I never understood why everybody copied this Chrome thing.

The address bar does change. The status of tool bar items can change.
That’s right, I’ve never thought about it.

You’ve changed my mind on this.

It is a different location bar for every tab. Try typing some text into it and then switching tab and then back again.
Yup. I’ve been wrong for years.
I can see reasons why a lot of things would go under the tab, like the address bar. FF's biggest UI-sensibility sin I know of (at least on the last design—I've not used the new one yet) is the damn hamburger menu. On desktop! That's a real WTF.
If you're on Windows, press the [Alt] key to get the ordinary Windows menu bar. Can't recall, might work on other OSes too.
I don't consider Photon a skeuomorphic design really. It was a grid based flat functional design with razor sharp edges. Australis on the other hand was absolutely skeuomorphic, color gradients to give pop-out with curved tabs to mimic real folder tabs and so on.

If "the element is connected to the content it represents" is enough to make a design skeuomorphic then so be it but either way I don't think it's desired "because that's how real folders work" vs "I want to know which UI elements are related".

A tab bar should look like a tab bar. Even if that look historically is skeuomorphic. In the same way that a save button isn't labelled with a floppy disk icon anymore, but with the save icon.
I'm with you.

It looks and feels FAST!

I don't like how skeuomorphism turned into a dirty word.

A skeuomorph is just an unessential design cue a derivative takes from the original. They can be entirely ornamental (like the dumb faux leather of some of the latter day Jobs-era iOS apps), but they're quite useful as affordances.

There's no particular technical reason why you'd prefer any one particular graphic design for tabs over another, but the separator-style tabs make the association between tab headers and contents much clearer than the new design.

Likewise, there's a lot of value in the Numi/Soulver style of calculator apps for power users, but common users are better served by the skeuomorphic physical calculator design, which is perfectly functional and much more familiar to most (though this may change as younger generations are less and less exposed to traditional calculators).

Alternatively, if you want to flip back to the old UI in Firefox 89, you can go to about:config, search for browser.proton.enabled, set it to false, and then restart. That should do it too.
For how long, until they remove it? Honestly, I hate Firefox now. It's going backwards.
Hopefully after the next esr comes out so I don't have to deal with this for another year
I think you can safely assume they won't throw it away instantly. Unless they introduce some new feature that is only possible with the new UI, Mozilla will probably just keep it around to appease fans until they redesign it again.
No, they are confirmed throwing it away in the next release.
Huh, on Arch GNOME it does not go back to the old interface, but it does make the new one more compact for me. That is far more workable for me.
As long as tree style tabs still works , it's all good.
This is the feature firefox needs to be in the default browser. All these tweaks to the top tab thingy is just a band-aid on the fire.
Works but looks differently with less emphasis on the current tab.

I haven’t gotten used to it yet, but oh well.

Isn't that a user preference? I remember after some upgrade a few months (maybe a year?) ago that the current tab was also de-emphasized and I changed the highlight color as it didn't seem to be changing itself back in the next release (i.e. not just a bug) although it never manifested on my private laptop which runs the same setup.

Edit: Apparently you need to set custom CSS for this. You might need to enable Expert Options at the top of the preferences screen. I've got:

    .tab.active {
      background-color: #371737;
    }
    .tab:hover {
      background-color: #600;
    }
These colors are I think slightly more obvious than the default was; just toy with the values a little (lower is less color / darker and vice versa). Not sure if this part of my CSS is also relevant / needed to work well with these colors:

    #tabbar {
      background-color: #000;
    }
    .tab {
      background-color: #171717;
    }
Do you use it along with the regular tabs ?

I liked the tree style tabs but didn't want to have two components basically doing the same thing taking up my screen space. I don't know if there was a way to hide the regular tabs.

I can hide the whole tab bar when using TST, but doing so will also hide the window buttons (minimize/maximize/close), which is annoying.
It's been a while since I used a Mac so I can't speak to that, but this is categorically NOT the case on my Linux (Kubuntu) and Windows machines.

I have TST enabled with the "regular" tab bar disabled, and can very much still see/use the window buttons.

Can you share your style? This is what I use on Windows

    #TabsToolbar {
       visibility: collapse;
    }

    #titlebar {
        visibility: collapse;
    }
and the result:

https://i.imgur.com/0DxPCvE.png

Sure, this is what I use on both machines:

    #main-window[tabsintitlebar="true"]:not([extradragspace="true"]) #TabsToolbar > .toolbar-items {
      opacity: 0;
      pointer-events: none;
    }

    #main-window:not([tabsintitlebar="true"]) #TabsToolbar {
        visibility: collapse !important;
    }

    #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
      display: none;
    } 
It's probably worth noting that I've also set "browser.tabs.drawInTitlebar" option to "false" in about:config.
I think there's a standard Firefox preference to un-merge the tab bar and window bar. Maybe that would help?
I can't find that option, do you know where it is?
Menu → More Tools → Customize toolbar

Then click the "title bar" checkbox at the bottom left.

A checkbox labeled "Title Bar" at the bottom of the customize window
I used to use tree-style tabs with the normal tab bar hidden. I've moved off Firefox so no guarantee the new big update hasn't broken this, but I used the following userChrome.css (if you're unfamiliar with that then check out https://www.userchrome.org)

    /* Hide tab bar in FF Quantum */
    @-moz-document url("chrome://browser/content/browser.xhtml") {
      #TabsToolbar {
        visibility: collapse !important;
        margin-bottom: 21px !important;
      }

      #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
        visibility: collapse !important;
      }
    }
I think I probably got it from here: https://www.reddit.com/r/FirefoxCSS/comments/d4hx49/ff69/

Edit: More authoritative source shared in the comments which is probably a better starting point (and has loads of other configuration too): https://github.com/piroor/treestyletab/wiki/Code-snippets-fo...

I just tested this on the newest release and it works! I was looking for something like this. Thank you :)

(It does seem to hide the min/max buttons on the left, but I don't use those anyways)

If only tabs were the only design problem with the last two releases.
Looks like this might only be an issue with dark-mode. In regular mode the active tab is very visually distinct.

I think this is a more general problem with dark-mode interfaces. Contrast of content is usually easy to achieve (e.g. light text on dark background) but getting contrast between UI elements like tabs is quite difficult.

Apple had a great talk about the design challenges at WWDC 2019. One of the ways they do this is by integrating ambient colours from things like the desktop wallpaper which Firefox doesn't do.

The problem that tabs no longer look like tabs (and that the active one has this weird button look) is not exclusive to dark mode.

In one word: Why?

>In one word: Why?

In two words: Why not?

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Tabs are so 2010s

(Joking, it is a textbook example of ergonomic regression for the sake of change).

My only big issue with the redesign is that it no longer shows you at a glance when a background tab is playing audio. You have to mouseover each tab to show the audio icon.
It displays for me, in place of the favicon (but I'm on nightly, so this might be a more recent change). Here's what it looks like for me: https://imgur.com/a/EwaKsNt
Interesting, here's what I see now on 89.0: https://imgur.com/a/bItmejF

I swear the "PLAYING" text wasn't there when I first updated. Seems like maybe they're still ironing out how to handle it.

FWIW, the playing text is longer in the localization I use, and when cut off (many tabs) it's not really readable. :)
The difference is compact mode. In compact mode it replaces the favicon, in normal/touch mode it adds an extra line with the "PLAYING" text.
> an extra line with the "PLAYING" text.

If anyone knows how to turn this off, or prevent it moving the tab title up and down please let me know.

Pausing a video in one window then a second later having my attention drawn back to it by the movement is very annoying. I'm on xubuntu.

(comment deleted)
I'm using ESR, so this hasn't impacted me yet, but there's a large userChrome.css file that reverts the worst of the changes at:

https://github.com/black7375/Firefox-UI-Fix/

It's well commented enough that you should be able to cherry-pick individual fixes.

(comment deleted)
Thank you. With just the fix to connect the "button" to the tab below, it feels good again. The other interface with the floating buttons is a bit too unspatial for me (I always had a thing for spatial interfaces).
It would be pretty cool if someone could create a package management-like tool where I could easily browse and install these little customizations…
Perhaps an extension or plugin of some sort... maybe call them add ons? ;-)
Yeah, except the "new"-style Firefox addons can't do half the things ye Olde ones could.
Would userChrome.css get overwritten with each update?
No, but your changes may break in a future update
I like some of it but really wish they would just add a connection graphic to the page so they are actually tabs again.

Also I know some people are mad the menus are too tall.

ProTip don't try to disable the new "proton" menus its all whacky.

I've also been sticking with ESR for a while, and wondering how much time I have until the apparent trainwreck that is current Firefox development catches up with me. Android browsers have already gone to unusability hell ever since the firefox redesign, to the point that I've given up on browsing from mobile entirely. I can't even imagine dealing with the same levels of brain damage on desktop. What's the next step, giving up and switching out to Chromium?

Every time I have to use either Chrome or a recent version of Firefox(or any version with default settings, really) it's a terribly frustrating experience.

Until now about:config browser.proton.enabled false works fine.
Revert to the older, compact tab style using:

1. Visit about:config

2. Set browser.proton.enabled to: false

3. Set browser.uidensity to: 1

4. Optionally, set browser.proton.toolbar.version to: 3

No userChrome.css edits necessary.

This pref will not work in future versions.
Sure, but my hope is that if every discussion of Firefox talks about how we all prefer it, Mozilla might realize it's in their best interests to review their decisions, before they annoy the last vestiges of their userbase away.

We can only hope, anyways.

The first day 89 was out, I got a call from a user wondering what the heck happened to Firefox, and if I did something.

There about 10 issues logged with Bugzilla regarding this. All closed as "wontfix"
Thanks, just adding

    .tabbrowser-tab[selected] {
        background: #fcb731 ! important; 
    }

Already makes the active tab visibility so much clearer.

I just did a check, they use #FFFFFF for active tab and #F0F0F0 for non active tab.

Using https://webaim.org/resources/contrastchecker/

Gives a contrast ratio of 1.13:1

A big fat fail

Note that these numbers are intended for text readability. They don't directly relate to the visibility of a rectangle.
Firefox, despite its questionable UI design choices, is heavily customizable with the userChrome.css file. The author mentions having to figure out the correct ID/class names, but you can do it yourself just by inspecting the whole browser chrome as if it was part of an HTML DOM.

Browser Tool Box (open fly out menu -> More Tools, or Ctrl+Alt+Shift+I). This opens a remote debugging session, and you can freely select and customize any part of the chrome.

You’ve got to enable that first: dev tools → Settings → Enable browser chrome and add-on debugging toolboxes.
And Enable remote debugging.
That’s pretty neat, but it doesn’t justify their UX decisions. Why change something that seemed to work well? Do they have constant feedback on their previous design?

I’m still confused why the tabs look like this. The active tab is so different than the inactive that it’s hard to make a connection between them. Most people already have an association with typical tab UIs. Why change this fundamental perception into something more generic and ambiguous?

> but it doesn’t justify their UX decisions

It doesn't justify shitty UX decisions, no. But it does alleviate the pain you experience when companies (inevitably) do fuck up something you depend on.

If the same happened in Chrome or Safari you would have the same chance of adjusting the browser UI as you have adjusting the UX of your toaster (none [or with a lot of work]).

Instead, Firefox lets power users be power users, installing extensions that completely changes the UI or adding your own stylesheets for customizations like the ones mentioned in this submission.

So booo to the team doing the UX change, yay to Firefox for letting me fix their own mistakes without having to wait for it to be deployed.

> Most people already have an association with typical tab UIs. Why change this fundamental perception into something more generic and ambiguous?

This was probably said about tabs vs windows when tabs first appeared in browsers as well. Why introduce a different concept when you can already have many windows?! People seem to prefer tabs today, so sometimes going against the wind is a good thing. Problem is that you don't know what will be good until you throw that thing at people and they tell/show you their reaction.

> This was probably said about tabs vs windows when tabs first appeared in browsers as well. Why introduce a different concept when you can already have many windows?!

You can justify any bad changes this way and "probably" means you don't know but you just made it up to justify. Tabs made things better we all new when that happend. What good thing the designers thought to introduce this change like in the tabs?

These designers have nothing to do at office if they don't. Basically we all are lab rats with every new shiny device or app version that hits now a days. Anyone having fun re-learning new gestures on mobile devices every 2 years?

I like the new tabs. They don't confuse me. And they look less noisy/calmer/less crowded. The Windows task bar also works nicely without a tab design.
I applaud the Firefox team to make it possible to customize the UI at such level and I hope that it spawns a lot of beautiful plugins.

My biggest gripe is that the default UI doesn’t look like a typical default UI. It looks like a third party plugin that’ll most likely confuse more people than with a plain boring UI.

You can still have many windows, nobody stops you from doing that.
> This was probably said about tabs vs windows when tabs first appeared in browsers as well

Tabs is a way to group related so windows which useful if you have many of them. And AFIR tabs in browsers was very welcomed by users, unlike today’s nonstop UI churn.

> Do they have constant feedback on their previous design?

Why listen to feedback when you have telemetry. (edit: /s for clarity. My point is that telemetry is probably a net negative for many projects.)

There's probably a telemetry -> spreadsheet -> powerpoint -> jira workflow that people are doing full time at most companies.

Taking your comment at face value: because telemetry can lie even more easily than users, pointing the finger at entirely the wrong thing in the worst possible way: with cold, hard numbers to convince most people who don't want to deal with the issue.

Telemetry complements feedback, it should never replace it entirely.

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A reasoning given for the change in tabs was a lot of user feedback that people didn't know you could drag and drop to rearrange tabs, but also kept requesting that ability (despite it already being supported). I can almost see the reasoning behind "the attached tab looks far too attached and 'fixed' to the rest of the window so floatable buttons would appear less so and 'easier' to move" and I don't entirely fault it for bad logic, though I also think they could have found a better alternative that didn't feel so drastic a departure from decades of tab UIs (in Firefox previously and elsewhere).
Says a lot about the users, when they request an existing feature without trying to do it. I mean it's a simple drag and drop. How do you not try that before? :D
Partly because due to a decade (or maybe decades?) of constant UI/UX churn in software, operating systems, etc. people are scared to try things for fear of breakage and inability and/or ignorance of how to undo unwanted changes. Speaks to the overall terrible and continuously worsening state of software UI/UX
one caveat is that you need to both enable remote debugging and enable browser chrome debugging toolboxes in the settings. fairly easy to do cmd-option-i then f1 or click the three dots and settings. then under advanced settings there are two checkboxes to check one for remote debugging and the other for browser chrome
I have a pretty customized userChrome.css as the main feature I use in Firefox is multi-row tabs. This used to be provided by a XUL extension but now it possible in a somewhat less fantastic way with userChrome.css.

The problem is that every major UI change breaks the userChrome.css and I have to spend a while tweaking it or waiting for someone else to design it up. It's frustrating.

Since I knew this update was coming I disabled automatic updates for the first time ever. It might be a while before I decide to upgrade.

It sounds like you should be using the ESR releases?
Especially since there are some potential RCEs in Firefox 88 as far as I can remember.

ESR is definitely a safer option.

You know "Simple Tab Groups"? It's far better that having multiple rows of tabs.
It doesn't fit my workflow. I open almost every link in a new tab and if I'm doing research that can be a lot of tabs. I don't want to spend any time organizing these temporary tabs; I just want a way to quickly see and move between them.

If you use a lot of tabs in most browsers, the tabs end up being just tiny icon-sized. That's no good. I also don't want to go through another layer to find them.

I do the same thing (and by default each new tab opens in a new temporary container). I use Tree Style Tabs to be able to organize them. It's particularly nice with a wide-screen monitor, since vertical space is at a premium but there's extra horizontal space. It just makes more sense to use that for the tab bar. I do have userChrome.css to hide the main tab bar though.
Changing designs is what made me realize the need to push for free software and appreciate people like Stallman. I don't want to use the modern, awful designs for Firefox or Android. I prefer firefox as it was before this update, the original skeumorphism of iOS, and Android around the galaxy S3 era. It's incredibly frustrating that my user experience has to continuously degrade over the years just so managers and UI designers at these companies can justify their promotions. I immediately disabled the firefox proton changes and will continue to use the old UI or switch browsers when it's no longer possible.
What is the link between free software and changing designs?
Can anyone explain why companies like to make unnecessary design changes? It seems to be that there’s no benefit to this tab change. Other products like Discord and Google Meet have also been making slight UI changes recently and I find it nothing but a nuisance.
There is a certain amount of allowable "thumb twiddling" time.

My educated guess is that someone working in a private company has to justify their salary, even when there is nothing to do. So they come up with "absolutely necessary work to do" by inventing themselves solutions and "improvements" for problems nobody has.

Now we have a team of +10 people doing meetings, colorful charts, analysis, etc. Including writing blog posts like "changing the world and fighting a pandemic by changing the size of the tabs". Bosses raise the head and see all the cubicles busy. Everybody is happy.

Now that it's released it's time to think about the changes for the next version.

PS: I'm a happy Firefox user since it was just "mozilla".

(comment deleted)
1) actually-necessary design work on a product is very boom-and-bust.

2) for years now, tech companies have hired enough designers for the boom periods, rather than contracting or just dealing with longer design cycles—I suspect this is Apple's influence leading to much larger design budgets and resultant empire-building.

3) bust-period design work doesn't get one promotions or look as impressive in a portfolio as boom-period design work, so design departments or individuals are heavily incentivized to create artificial "booms" both so they have enough work to do and so that the work is helping everyone advance their career. These align well with product manager career advancement incentives (everyone loves screen shots) so they get green-lit. These are the unnecessary and often ill-advised redesigns that we see so often.

Because they retain oversized permanent UX teams with insufficient work to go around. The result is endless user punishment. Mozilla could improve their browser and save money in one simple step
First they'd need to revert all the oddities of the last few years, like the growing url bar, now weird tabs, and hardcoded colors in about.
UI visual design has a propensity for bike shedding.
Despite all this criticism (because negative 'insightful' comments are what drive clicks nowadays), I just switched back to Firefox from Edge BECAUSE I love the new tabs' appearance.
That is good to know, because what I am most afraid of is this new look driving away people, or making people not switch to Firefox.
I mostly like it, especially along with container tabs.
I think it's a bit of a nice improvement, or just different in a way I don't mind. Which is a sentiment that doesn't provoke me to make forceful statements about the change being good or bad.
I'm in the middle ground. When I first heard the complaints, I thought I was going to hate it.

After using it, I simply don't care. It's fine either way to me.

I don't care that much about the tab change, but the contrast against the background for the URL and search boxes has gone waaaay down, to the point where I'm finding it noticeably slower to acquire them. (I have to look for the text in the box now, rather than the box itself, because the latter is nearly invisible.)
I used to use Safari, until Big Sur came out and ruined its UI by making the contrast way too low -- I was having trouble even distinguishing where the page content ended and the browser chrome began at a glance.

So I switched to Firefox a few months back... It's disappointing that they've now made exactly the same mistake, but at least there's Firefox Color [1] that allows me to easily restore some contrast without spending time writing my own CSS.

[1] https://color.firefox.com/

Exactly. First impression is meh, but I'll get used to it. Whatever.
I like to bash Mozillas new direction, and I was fully prepared to jump on the UI refresh hate bandwagon.

But I don't know why I hardly noticed a difference. I mean sure it does look like a button, and I don't really get the point of it, but the thing I was worried about was the increased screen estate. Maybe it's because of my gtk theme, maybe it's related to fixes in hidpi UI scaling, but it actually seems to use less screen estate to me.

Am I crazy? Or are there other people that feel like its using less screen estate?

They fixed some things partway through the process with the compact theme - the address bar is now shorter while the tabs + their padding is taller than the tabs in old compact mode. I haven't done a side by side but I think compact -> compact ends up being a wash in vertical real estate. There were some older images where new compact was taller than old normal and new normal was taller than old touch when it was in firefox beta however.
I also like the new design, but I switched back to Safari after a day because Firefox kept taking 150% CPU. It was actually really snappy at first. I'm not sure what happened. But yea it wasn't just a one time thing.
I use firefox all day long on apple with zero issues. Sure it wasn't something on your system? like an errant plugin? (yeah I have a memory/cpu graph running 24/7)
Hm, I didn't try disabling plugins. Good call, let me try that.
When I see that, it’s usually because one of my tabs has a site with something in it like an endless scroll list or something else inefficient that allocates tons of elements in the DOM and never releases it.
Hm maybe. But I only tried sites that I already had open in safari with zero problems. Someone else suggested maybe a plugin was screwy; that seems plausible to me.
I actually love the tab design, which is odd, because I hate anything new. What I did NOT like is the vertical spacing, which stank of the superfluous header bars from the late 90s/early 2000s.

I applied a browser CSS change to fix it, and now I think it's great.

    /*
     * remove dead space in browser tabs bar
     *
     * Source: https://www.reddit.com/r/firefox/comments/nq6kto/if_you_dont_like_the_new_design_you_can_disable_it/
     */
    :root { --tab-min-height: 30px !important; }
    :root #tabbrowser-tabs { --tab-min-height: 30px !important; }
I also am in this camp, and used the "compact" UI theme previously. With editing the-

about:config

I have the new tab theme, and the compact UI once again.

And if anyone is also trying this route - change `browser.uidensity` to 1 will restore the compact theme.

This indeed looks much better. Unfortunately this will be removed starting FF90, according to the reddit link above.
Oh, well looks like I'll need to delve into editing the browser's .css now to adjust it to my liking.
I'm in agreement with you here. I do like the design, just loathe the excessive useless margins. It's a web browser, not a web site. I don't know why everything needs massive margins/padding nowadays. I like condensed.

Anyway looked a lot worse in screenshots, with my system theme and tweaks I am actually liking how it looks. What I don't like very much is the new shield icon inside the address bar, looks more like a weird hexagon than a shield, but that's rather minor.

thanks I hate that the browser is taking that much space. browser purpose is to serve content, not to be in the way of content.
It is a bit hard for me to form an opinion on the UI design as yet. But this release has been forced on me by their auto-update feature (no choice to wait with updating), and since then after opening FF it freezes my entire Ubuntu 18 to the point where I have to restart. In app reviews I saw I wasn't the only one with this issue.
i've been seeing FF freezes on arch too, though thankfully just the browser (which i need to xkill) rather than the entire desktop
Are you on macOS? It seems most of the people liking them are on this OS (despite the article's author). I wouldn't be shocked to learn that all these Mozilla designers are using macs :)

Personally it's unusable on my Windows 7 computer. I know it's a dead OS but still.

I'm in Linux and I like it, although some userChrome tweaks applied to it already, and it's respecting my system theme/colorscheme, so it looks actually kind of good.
I'm using LMDE4 and it's working well for me.
As someone who uses Firefox as their daily driver consistently for the past several years, when I first heard that compact tabs were going away I was pretty disappointed and a little annoyed. However, I installed Firefox 89 just to give it a try and I actually rather like the new interface.
I used to browse with FF and Google Chrome. But now FF is so similar to Chrome that I hate to Alt + Tab and be unable to tell them apart.
(comment deleted)
I really loved the new colorful theme, IMO it looks just so modern and fresh.
I thought I'd hate the new tabs but it turns out, I really like them!
This hasn't affected me at all; thankfully I use tree style tabs[0] with some CSS a friend shared:

    /*Collapse in default state and add transition*/
    #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] {
        overflow: hidden;
        min-width: 40px;
        max-width: 40px;
        transition: all 0.2s ease;
        border-right: 1px solid #0c0c0d;
        position: absolute;
        left: 0px;
        z-index: 20;
    }

    /*Expand to 260px on hover*/
    #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"]:hover,
    #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar {
        min-width: 260px !important;
        max-width: 260px !important;
        margin-right: -220px;
    }

    #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] + #sidebar-splitter {
        display: none;
    }

    #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] > #sidebar-header {
    visibility: collapse;
    }

    /* hides the native tabs */
    #TabsToolbar {
        visibility: collapse;
    }
    #titlebar {
        visibility: collapse;
    }

This provides the benefits of tree-style tabs without constantly taking up horizontal space.

[0]: https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta...

I have found myself to like this new style of tabs, despite not liking it in previews in the announcements.
I think the purple theme is pretty so I enabled it.
I mostly liked the new UI, except for the changes in the tab bar, the major one being reducing the tab width to mirror Chrome's. When you have more than a few dozen tabs open in Chrome or the new Firefox, it becomes near impossible to know which is which. Fortunately, I found an about:config property to change it:

Visit about:config and update browser.tabs.tabMinWidth to 100 or 110, whichever looks better to you.

Is there a way to separate UI/UX from functionality/security?