On Sat, 2021-02-20 at 11:41 +0000, Patrick O'Callaghan wrote:

The last 2 or 3 kernel updates seem to have triggered a regression in the i915 (internal Intel GPU) driver. I get damaged screen updates, very noticeable tearing on videos and occasional freezes in the DE

I may have a similar problem. See my thread "Strange Artifacts in the Panel"; the problem seems to affect the whole KDE Plasma subsystem, but not other functions.