Framegen has to be used on a game where I have 30-40fps.

If I have 29fps, my character lags like they're drunk.

If I have 50+fps, I don't need framegen.

Cyberpunk 2077 is the only game I use it on.

That's fair. I mostly use framegen to get from 40-60 fps in games. You stop seeing the artifacts pretty quickly, even with something like Losseless Scaling, which doesn't have access to internal game data like a native implementation would.