I tried following my own advice from this question, but the workaround there failed to work in 19.10 while it worked up until 19.04. The tearing (applying the tweak in the linked question) is reduced, only the upper part of the screen has tearing now, but it still isn't completely gone.
It is once again a firefox specific issue (chromium and the electronplayer snap don't have this issue). Are there any other workarounds to reduce tearing in firefox other than the aforementioned one?