VRR does not work if you have a NVIDIA card and more than one monitor enabled.
I recently learned that’s not entirely correct for Wayland. The critical thing is that VRR stops working if more than one enabled monitor is connected to the NVIDIA GPU. Meaning that if you connect only one display to the NVIDIA GPU and the other monitors to the integrated GPU it should just work.
I felt pretty stupid when I realized that I could’ve just switched a single cable and be using VRR way earlier. Didn’t even need a reboot to work. For reference, I’m using a NVIDIA GPU + AMD CPU with 1 G-Sync as my main monitor and one non-VRR as my secondary monitor.