That's strange. Did your browser update recently or crash unexpectedly? Sometimes that can log you out of sites. Also check if any extensions or security settings might be clearing cookies automatically.

I know for sure that extensions do not automatically clear cookies.

As for Firefox crashing, this browser tells me "Your tab has crashed" almost every day. I have a fairly old computer, so I think this happens because I try to open 6-7 tabs at the same time and because of this one or two of them "Crash".

Maybe there is some utility or setting in the browser with which I could check this, maybe there really is a problem in the browser and frequent tab crashes - is this some kind of error or a consequence of incorrect settings or something like that?

Yeah, me too. Today, when I started the browser, I was logged out of all my accounts, and I didn't do anything. I don't know what caused it; I thought it was just me