Hello,

please check if "Don't use optimizations for windows games" is deativated. It should be turned off. Win11 just checked this point for me for FFXIV and it begun to stuttering / no VRR in borderless windows mode.
Please also turn off "Game mode" in Win11. Turn off all options in FFXIV Display Settings below Refresh Rate - select No Limit.

This helped me getting VRR back to work with FFXIV.
Can you try monitor your PC while FFXIV is opened? Use HWInfo64 Sensors, check what happen when the stuttering appears., explecially for GPU usage / temp and CPU usage / temp.

https://support.microsoft.com/en-us/...e-f9389e535952