Same, Firefox on Android is extremely buggy for me. I experience frequent crashes because I have too many tabs open at once. Multiple times per day, I have to restart the app because the theme will bug between light and dark, which makes some of the UI text unreadable. And sometimes when I restart, I lose some of my most recent tabs for some reason. Very frustrating, but Firefox Sync and extension support are essential for me, so I deal with it.
By the way, I actually use Fennec from F-Droid and not Firefox from the Google Play Store, if that matters.