My PPSSPP home and games blink with strange points

[LunaMoo]

Clean your monitor, we can't see a thing under that dust.

But seriously, this could be your GPU overheating or a driver bug. In the latter you could try different backend or different driver, especially if that's windows 10 which likes updating stuff behind your back and it's often broken;p.
If it's overheating, the joke might be real - dust is primary reason for pc's to overheat, most people never dust off the case inside and it has to be done regularly, otherwise it stops radiators from doing their job radiating the heat away from hardware that wastes a lof of the electricity on heat.