When I Requested Amazon's Data on Me, I Didn't Expect What I Would Get Back (theguardian.com)

I find it incredible that anyone would use a Kindle (or similar device) when they know beforehand that data-gathering is the name of the game. I find it even more incredible that they are actually surprised by the extent of the data collected.

I've a different worldview wherein I automatically assume that any online, phone or interactive activity that I engage in will be monitored and recorded automatically and I take steps to either not engage in them or I actively take steps to nuke the data collection.

could we unclickbait the title?

I suggest: "Every highlight tracked on Amazons Kindle"

Kindle highlights are a cloud service. You can even browse them on https://read.amazon.com/kp/notebook

of course they are stored....

From what I read there might even be a toggle option for "annotation backups" in the devices settings.