I'm using Firefox as an example, but this happens on Chrome too.

When I launch Firefox in full screen, it works fine and I can enter and exit it. When I make the window not fill the screen, I can still enter and exit full screen. However, when I make the window fill up the screen again, pressing F11 results in a black screen. The website still works, and I can hear audio and type text (without seeing it). Here's a video.

I am running Arch Linux 5.8.14-arch1-1, with KDE Plasma 5.20.0. Happened when I updated KDE.

I have a GTX 1650, but I doubt that's the problem.

Any help would be appreciated, thanks!

Does it happen regardless of DDX driver in use?:

1. modesetting (FOSS; upstream default)
2. nouveau (the other FOSS option)
3. nvidia (proprietary)

I'm having this issue with vivaldi as well. MSI gaming laptop with optimus intel/nvidia, using nvidia and Intel or modesetting drivers, with and without nvidia modesetting enabled.

I feel like it's probably to do with a compositing effect, but haven't bothered to figure out which one.

If my browser is not full screen to start with, the video can be full screened w/o issue.

If the browser is full screen, taking video to full screen just goes blank.

Ah. I found it. There's an effect "Full Screen" in "Desktop Effects" that needs to be disabled. It's supposed to do some kind of animation for windows going into and leaving full screen mode.