Full screen games stuttering on Wayland (GNOME 42 regression)

Affected version

• Arch Linux
• Mutter 42.0
• Wayland only
• Mesa 22.0.1

Bug summary

After update to GNOME 42, full screen games look like they are running at <60FPS, even though the game reported stable 200FPS. Tested with xonotic-sdl, this happens when running the game as native wayland client, or though XWayland.

There is no stutter if:

• the game is run in windowed mode (unless the game window covers the whole screen, including the shell top panel)
• there is any window on top of the full screen game (i.e. set "Always on top" on any window while the game is being played behind it)

Affected system is XPS 13 9360 with Intel HD 620 graphics (iris driver).