Update: first time i have seen the DE have the loop issues, as certain icons in the taskbar stutter like mad. Honestly no clue why this is happening, but this is a new development, so maybe it can help narrow things down.
This sounds like the same problem Iāve been having (started maybe a month ago for me). I have not been able to find an actual proper fix but I have found a temporary workaround that you could also try, which is to turn off kwin compositing (shift+alt+F12 to toggle off/on). For me this entirely removes all of these strange issues with window contents not updating, looping and/or flickering. The cost is losing all the compositor effects of course so itās not ideal but at least the annoying stuff is gone.
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Well I will try it out. The BIOS update has changed things a bit. Used to be that the stuttering only affected videos, it now affects the rest of the window. Just a moment ago, in Firefox, I had it happen that not just the youtube video looped, but the youtube icon in the corner āstutteredā moving up and down quite rapidly.
Very strange. I will attempt your fix next time. Who knows, toggling it off and on would help.
Just clarifying that I personally keep the compositor off. I donāt toggle it back on because of how often these issues occur with it on.
I should also add that sometimes you might have to restart plasmashell afterwards as well (plasmashell --replace) if it looks like something like the task manager gets stuck in an unusable state or something. This might happen especially if you keep toggling the compositor off and on repeatedly.
I just tried disabling and re-enabling the compositor. It does resolve the issue but only for a short time.
The most baffling thing about this issue is that it only impact applications one at a time.