Hi, I’ve been having similar issues here — after using other windows and returning to Obsidian (or sometimes when maximizing Obsidian), the entire window area (including the titlebar) is simply filled with black or white. I’ve also had rare occurrences of parts of the window being occluded by white rectangles and not redrawing. Restarting Obsidian always fixes the issue.
I’m on Pop! OS 20.04, also with GPU acceleration (NVIDIA 440.100). I agree “upstream” sounds like the right way to label this, though I don’t know where to go to report this. Happy to help diagnose further.