Comment 19 for bug 1895905

I'll note

https://bugs.launchpad.net/ubuntu/+source/sddm/+bug/1865837
"Lubuntu 20.04 qa-test install; flashing at sddm greeter when mouse at top panel (pre-login)"

which reads very similar, maybe even same cause (similar pattern at least in flashing), but occurs different positions on the screen.

This was not the duplicate I'm hunting for...