[viseztrance]

For what is worth, I have disabled it in firefox 90 in about:config.

[jffry]

I did as well; Firefox 91 no longer has that option. You'll be Proton-ified if you upgrade.

[ddek]

I do too, but for about a month or so I've had proton anyway.

I use FF developer so I'm a bit ahead of everyone else.

You can fix it with some userChrome.css changes. I'm scared to touch it for fear of fucking my 'tabs on the bottom' css.