This MR just got merged: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19125

Which completes the tearing protocol: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/65

So once the mesa update lands, XWayland titles should be able to tear under Wayland, at least on AMD GPUs. Nvidia will have to provide support in their drivers in the future.