Wayland support for EGL_ANGLE_sync_control_rate
Initial implementation of "EGL_ANGLE_sync_control_rate" extension was added in MR !17815 (merged)
Wayland is mentioned in the MR description, but looking at the commits it seems that MR only adds the generic extension stuff and egl/x11 support for EGL_ANGLE_sync_control_rate, eg. it mostly touches src/egl/drivers/dri2/platform_x11 files. Maybe the MR description actually meant XWayland?
Recent fixes and improvements MR: !20665 (merged) which again touch x11 specific stuff.
So it looks like native Wayland support for EGL_ANGLE_sync_control_rate extension is still missing from Mesa (unless I missed something), and thus should be added, as there are no other EGL video timing/synchronization extensions available either.
Chromium has support for EGL_ANGLE_sync_control_rate, and Firefox is looking into utilizing EGL_ANGLE_sync_control_rate aswell, as it would allow using the same EGL code for both X11 and Wayland.
Mesa commits related to EGL_ANGLE_sync_control_rate extension: