I have no issue with KDE Wayland and SDDM-git when using AMD GPU. No need to use this config /etc/sddm.conf.d/10-wayland.conf
Real freesync works flawlessly on Wayland.
My guess is you use Nvidia GPU, but Nvidia and Wayland are not friends. Switch back to Xorg.
Don’t forget, you should [HowTo] Provide System Information.