The poor uniformity, aggressive color shift when only slightly turning the phone, yellow screens, dust in camera lenses, are absolutely real issues. Just because you never experienced it doesn’t make them non-issues. Not saying that’s what you meant, but you are lucky to have not gotten any dud devices.
There is variance among screens, it is the nature of OLED. This whole brightness issue that people are experiencing, I think has something to do with Apple adjusting the brightness settings from the 15 to 16 series (16 gets much dimmer at low brightness).
My 16PM is brighter than my wife’s 16PM at the same brightness slider setting at certain points. The max and min brightness levels are the same though. Seems like there is some more variance than usual with the 16 series considering how dim it can get at the lowest setting.