Comment # 22 on bug 1183676 from Christianito

The easiest way to verify is probably switching on the monitor's frame
counter/refresh rate (the name can vary) via OSD to see its actual refresh
rate.

In my case, it shows a constant 144 Hz instead of the selected refresh rate of
VRRTest under X11. When using VRRTest under Wayland (and switching on Adaptive
Sync in KDE Display Configuration), the monitor's shown refresh rate is
adapting to the application's refresh rate confirming a working Adaptive Sync.

I was reproducing this right now under KDE using latest official Mesa on TW.