What you can test is checking if if it happens on a different distro, it is what I would do when I get the card, either just going with standard Ubuntu or more vanilla Arch distros such as Endeavour OS. After that I would check if it is specific to using a specific DE, since you used KDE in both your tests, lastly I would also check if it happens on Wayland or X11 or on both.
My guess right now is it might be KDE specific, since they switched to Plasma 6.0 recently I believe, there may still be some bugs with it? Though I still cannot replicate it on Nvidia even with KDE.