NVidia drivers only: Wrong thumbnails and flickering thumbnails in overview
Using gnome with the nvidia driver in the wayland session causes XWayland windows to have wrong thumbnails in the overview. The best way to describe this issue is by showing this screencast:
As you can see in the screencast, after the first XWayland window has been opened (Firefox), there is nothing unusual to see. But starting the second XWayland application (Visual Studio Code) causes both Firefox and Visual Studio Code to have the same thumbnail. Switching the workspace will exchange the thumbnail with one of them (and flickers during the switch), but regardless which thumbnail is shown, it is the same one for both.
Leaving the overview will show the correct content for the window, so only overview and workspace preview are affected.
Opening a third XWayland application will extend this behaviour to this one, too. This only affects XWayland applications (Wayland applications are unaffected) and it will only happen when using the nvidia driver in the wayland session.
This has been reproduced with mutter/master, gnome-shell/master, nvidia 418.56-2, xorg-server-xwayland 1.20.4-1