I think I’m being bothered by PWM, here’s a great post with an explainer. Over the last couple of years of using an OLED and FaceId on the new iPhone X models I’ve had spells on and off with eye fatigue and general focussing (yes, I’m getting old and had my eyes tested 😀). I found a few forums on people experiencing similar issues and started to use my iPhone less. Since getting the iPad Mini and using an LCD and most of the time I do feel like my eyes are a bit more rested. I’m not saying either way if the flicker on the OLED is causing me issues as I’m only just experimenting with it but wondered if anyone else felt like this?
I don’t think FaceId is a concern here, Apple have gone through testing to make sure it’s safe for the eyes but the flicker below 50% brightness has some credibility. Once I switch back to my iPhone 7 for a bit I should be in a better position to know what’s what.