Update: I realized that my iPhone is still flickering when I visit MacRumors on it, but it is only when an ad is on the screen. Can someone else with an iPhone 12 test this? If you're reading the MacRumors home page, for example, and an ad shows up on the bottom, my screen starts doing the flicker thing. If I x out of the ad, it stops. And then a new ad pops up shortly and it starts again.