The problem started right after I updated my system 3 days ago. On day 1 after the update, I was messing with Card-Forge when it started acting funny and then crashing, followed by Plasma showing no wallpaper nor UI (I can still see my other open apps, like a Terminal, Firefox, Kate, etc.) My monitor would go black, show open apps, go black, and then show apps again. Hot keys don’t work any more. This happened twice on day 1 with Card-Forge only, so I thought I had a new conflict to resolve later and moved on.
Today, day 3, I played a few hours of Helldivers 2. Upon quitting, so did Plasma with the same symptoms.
I can’t get this to reliably trigger, and it’s the third time to happen.