Ask HN: Why do I keep getting logged out of HN?

I've noticed I often get logged out of HN and logging in again just redirects me to the main page logged out again. It takes a couple days sometimes before I can login again. Using Firefox on android.

I thought maybe this is caused by posting something against guidelines, but it happens too often for me to be breaking the rules so much.

Then I thought maybe it's a way of dealing with load, since is cheap to serve cached static content from a CDN. I seem to recall HN does this, but it's new that is happening so often. I doubt HN is growing that fast anymore.

Maybe it's just a bug?