I woke up during the night and went to look at my phone, now I can see why people think this is unacceptable quality. I went to use my 12 Pro on very low (<20%) brightness in the dark, normal-ish use, and decided to look at this same wallpaper in the gallery and this happened: I got the grey-green screen. It's ugly. People are rightly upset. But then it went away so that the borders above and below the image in Photos were properly unlit. This does not happen at all if brightness is 50% or higher or when I look at normal images, where I get proper OLED behaviour and no grey-green light. Again, the Samsung A50 is all the way true black and I'm not sure why my 12 Pro seems to need a moment to sort itself out over the exact same picture.