Created attachment 110821 [details] #1 - "Before" - while errors were occuring. After a random period of time, the compositor begins to suffer breakdowns, not drawing window decorations or repainting windows as they're brought to the top. It's worse with OpenGL 3.1, but will eventually begin to happen on OpenGL 2.0 as well. Toggling OpenGL versions seems to temporarily reset the compositor and the problem is resolved. I'm attaching a screenshot, and two copies of "qdbus org.kde.KWin /KWin supportInformation" - a before and after. #1 is when I was supposedly running on OpenGL 2.0, but the compositor apparently died somewhere along the way. #2 is the "after" result when toggling the compositor setting to OpenGL 3.1. This happens with a variety of drivers (I've tried them all). My GPU - if it matters - is a GTX 1050 Ti.
Created attachment 110822 [details] #2 - "After" - after toggling compositor to OpenGL 3.1
Created attachment 110823 [details] Screenshot of errors in progress
I highly suggest to use the proprietary NVIDIA driver. Assuming an issue with nouveau driver. That driver unfortunately still does not have the quality to run a composited desktop