Do you happen to use Mac OS? I used a Macbook when I was working on my masters, and that's the only bad experience I've ever had with Firefox. It didn't seem to crash, but it ate memory like a black hole, and none of the suggestions people gave in forums ever worked for me, so I switched to Safari during that time.
Not Mac OS, but I am using a linux distro, and can confirm it's Firefox, as I've reinstalled everything from scratch and only Firefox seems to have this problem.
sane tab management and behavior on mobile versions along with proper syncing is apparently too huge of a hurdle to handle for the devs. these two are pretty much the only reason why i still use brave and not firefox