I am testing my game in the editor in Unity,

The issue is that Unity renders the game at maximum possible FPS, regardless of VSynch or screen refresh rate, or my attempts to limit it.

Turning on vSynch in Quality preferences doesn't help.

Also doing Applicaiton.targetFrameRate doesn't help.

Any idea how to limit the FPS?

I tried reducing my monitor's refresh rate via the NVIDIA control panel, it didn't change anything. So it's not even vSynched.