I just got a AMD RX6600 because I was having issues with my old gtx 1660 super. It’s not a big upgrade but I got this card for $120 (and it was only lightly used for 5 months by the seller).
I wanted to give wayland a try and It was working fine for a few hours but now, the screen blacks out every time I open or close an application.
I have tried restarting, logging out and logging back in. Also updated the system, mesa packages etc. (This is on a fresh install of Opensuse Tumbleweed, but I also had the same issue on my Artix install with xfce)
Strangely enough, the issue doesn’t seem to affect my Hyprland session much. Now it’s also coming in my Hyprland session.
The GPU works fine on Windows too. No black screen there.
EDIT: I fixed it. I enabled the packman repo at some point, which had slightly older packages and that caused the problem. Everything got sorted out once I deprioritized the packman repo and updated the system.
What firefox version? It could be that you are using xwayland depending on your or your distros settings. Maybe try setting
$ MOZ_ENABLE_WAYLAND=1 firefox
https://wiki.archlinux.org/title/Firefox#Wayland