I'm here to say ME TOO! I didnt even know this was a thing. I had an iphone 6 for so long, switched to the "big" iPhone 13 and now cannot use it.
Luckily, in the interim I used a Samsung a51 while traveling, and that is how I clued in that it is basically the phone, not me. I have no issued on a51 and can scroll for hours on end. But within minutes of using the iPhone 13 Pro Max, I start blinking and feel my whole eyeball get sore. it feels like its swelling. Curious, I researched and found more information on PWM and eye soreness. Its an actual thing. Wow. How did this pass? How can this be good for people. I'm glad I found this thread. I joined this forum just to lend my voice to confirm it is a thing! I hope they fix it.. otherwise I'll be buying another Samsung next time. I need an updated phone I can use.
For workarounds I have maxed out white point and maxed out brightness. This combination makes it not too bright but it hasnt really helped.
And to avoid actually looking at the screen, I use the "screen reader function" which is pretty horrible and reads every single thing on the screen so it causes more brain work to understand, plus the pronounciations are all wonky.
Anyway, Apple…. do better. I'll be going back to Samsung as soon as I can. i wish I knew this before, I would have returned the iPhone within days when I first noticed it!