I had two iPhone 15 Pro. I'm sure the second Pro had it. It is easier to spot if you compare the display with a display of an iPhone with LCD display. I could it see better on darker colours like red and with low adjusted brightness. Personally I think it is the Mura Effect as described
there and I think many iPhones are affected but people don't notice it because they operate with higher brightness adjustments. But I never experienced the screens as "dull".
The first iPhone 15 Pro had a really aggressive angular color shift, the second less but still disappointing, so that is a problem too. The first was built November 2023, the second October 2023, the second had a LG display.