Hi, I just registered to confirm this. I recently updated to 23.4.3 from 22.5.1 and have encountered a problem with osu and stumbled upon this post randomly while searching it.
The issue seems to come from the fact that the game goes out of fullscreen exclusive and becomes borderless. I have 2 monitors, so whenever something graphically demanding happens in a window on the 2nd monitor there are stutters, and also the Windows overlay becomes visible even though I disabled fullscreen optimizations. To recreate it easily you need to open the game, play a beatmap (there is a weird flash of black screen at a random point in the beginning of the map with this driver too btw), then you can exit to menu and alt+tab or hit the start button a few times and it will exit from fullscreen exclusive mode.
Hope they fix it, but until then you can use compatibility mode in the game options (it switches the game to D3D9, it also works great for me).
