Yep, I've tried turning Attention Aware features off, Face ID itself off, and covering the notch. No difference. Same with True Tone, I've experimented with that as well as Night Shift, white balance, etc.
As for an eye test, I absolutely would go in for one, except that I literally have zero issues with any other screen (Besides PWM-based ones). My desktop mac, iPad Pro, TV, other old iPhones, etc all are fine. It's just the XR screen, and I'm really curious to figure out why. The only thing keeping me from 100% thinking that's a placebo effect is that others on here have had the exact same symptoms.