VRR seems to behave in single monitor mode on my machine with driver version 545.29.02. However, games are a different story as they and many other wayland applications exhibit out of order frames / black flickering. Much of this can be fixed by patching explicit sync into XWayland, Xorg protocols, and Wayland.
Im currently running sway-1.9-dev @ 020a572e (wlroots based) with a patched wayland and xserver. This fixes black flickering and out of order frames when playing games through wine and proton. It’s not perfect, though. Performance in games is identical as far as ive tested (RDR2, GTAV), however, it feels as if there is some almost imperceptible frame pacing issue that result in the games not feeling nearly as smooth. Switching VRR on or off has no effect on this.
For those interested in testing this, youll need to start here:
XServer / Xwayland:
XOrg Protocols:
Wayland Protocols: