Never.! You’ll either end up with judder, tearing or increased input lag.Or just disable VRR / Freesync / Gsync and see how you get on?
Anyway in my case locking frame rate in Nvidia control panel to 118fps (this is what I use with my LG C1) reduced the flickering by a lot.
The funny thing is that monitors frame rate / refresh rate display still shows wild fluctuations from 80 to 150fps so it seems to be broken.