I also find the zenfone 9 struggles with refresh rates. I used to be in "auto" 99% of the time. I switch when gaming cause unfortunately it doesn't detect it should blast the refresh rate when gaming so I have to do it manually each time, which is annoying. But even once I set the refresh rate to 120 Hz in games, I see the frame rate glitch and sometimes go down under 100 creating a choppy feel.
When not in games, I also sometimes feel like it's not as smooth as it should be.
Also I find the battery drain is very quick when in 120 hz refresh rate. In my opinion, too quick. Overall a bit disappointed in this aspect of the phone.