The setting does not seem to work accurately even after switching to ‘Exclusive fullscreen’.
The 120fps setting limits actual in-game fps to 134 and putting it on 75 shows a steady 80 in-game fps.
There seems to be a 10% difference, not a huge deal but I wanted to play at 120 to reduce CPU/GPU load as it’s not an FPS.
One workaround is to set the Max Framerate in NVIDIA control panel which actually sets it to the correct value.