Just a random data point that may mean nothing or I'm not sure. I never had issues with PWM until I got my launch day 12 Pro. Kept it about 3 months but really suffered the whole time from headaches, nausea, and dizziness. Eventually sold it and got a Pixel 5. No issues. Got an S21 Ultra. Had issues a few days but was fine for a month after that.
Missed my iPhone so I went back to another 12 Pro as I kept reading the 12 and Pro Max had worse PWM. I was not optimistic anything would change but I gave it a try anyway. I've had the phone back for a week now. I had a headache the day I started using it but have been perfectly fine since then. Who knows if it my issues the first time were unrelated, if the 2nd phone is different somehow, if something with me changed? Who knows, but so far so good.
Missed my iPhone so I went back to another 12 Pro as I kept reading the 12 and Pro Max had worse PWM. I was not optimistic anything would change but I gave it a try anyway. I've had the phone back for a week now. I had a headache the day I started using it but have been perfectly fine since then. Who knows if it my issues the first time were unrelated, if the 2nd phone is different somehow, if something with me changed? Who knows, but so far so good.