General memory-corruption artifacting, such as pink checker-boxes around elements that are animating on the desktop. Swapping from fullscreen games would sometimes lock the system with a white screen (visually) until I restarted GNOME.
I’ve swapped over to KDE-Neon to see if Wayland might help, and it seems to have cleared up the artifacting but I can’t be sure until I test some games.
There’s also a possibility that the System76 power daemon was causing issues. I noticed that artifacts disappear altogether if I’m running any kind of GPU test, and I’ve seen some suggest that the GPU was running at a too low frequency. Would make sense if the daemon was the cause as that’s the other big change between Pop and KDE-Neon.
I’ll likely be back on Pop! when they bring out CosmicDE so I’ll try again then, but it might be that I avoid it for now.