This has been an issue for all Apple OLED displays since they came out. I bought the iPhone Mini when it came out but couldn't stand it because of the PWM on the display. I had to get an SE instead which used an LCD display.

I'm one of the ones who is very sensitive to this. I get occular migraines often. It has become fairly difficult to find displays that don't have these problems as everyone moves to PWM dimming on everything. Even lightbulbs are a difficult purchase for the same reason (at least Ikea makes some that have zero flicker and are cheap).