Comment 7 for bug 1954765

Hi, I have experienced the same behaviour, or a very similar one.

I also use KDE, and have a Intel/Nvidia hybrid system.
When on Power Save mode (I use Plasma Optimus to switch btw), on the first start of firefox in a session it just displays a frozen image of what was on the screen when I started it. If I kill it and start it a second time it works normally, and also on subsequents starts, until I log out and back in again.
This is also happening with the upstream firefox from the link in comment https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1954765/comments/6

Can confirm that switching to Hybrid mode makes the problem go away.

If you want me to collect debug information, let me know what you want.