Sometimes windows will just look like this? Minimizing or changing tabs usually fixes it, sometimes resizing. If I select a folder or a menu option it usually looks normal while highlighted. Happens most often with folders and with the software manager. Also happens to the text in Nicotine+ sometimes and the text editor. Never seems to happen to Firefox or VLC. I don’t even know what to call what is happening visually here so I haven’t been able to find anything just by googling.
The fact that screenshots have the same artifact suggests it’s an issue within the GTK or GNOME framework. I would think if it was an issue with the GPU or drivers the screenshot would probably look normal or at least glitched in a different way.
Unless the framebuffer is corrupted?