Someone was complaining to me that Apple took a long time to add 120 Hz displays to phones. I didn't even know what my iPhone had, turns out it's 60 Hz cause it's a 12 mini. I've used 120 Hz displays before. Cannot tell the difference.
Some people are born with nervous systems which aren’t capable of noticing the difference, just like there are people who can’t see better than 20/20 no matter how good their optical acuity is.
If you use a 120 Hz iPhone for 6 months and then switch back to your 12 mini, you'll notice immediately.