Ok so, I'm literally at the Apple store typing this. I'm not going to call this entire thread fake news, as there has been tangible evidence produced.
However, the stores 11 Pro Max is definitely brighter than my Xs Max. This is with True Tone turned off and auto brightness turned on but turned all the way up. NO LIE!!!
The stores unit is also flawless and uniformly white, with no hues to be found. Again, this isn't to minimize anyone having issues, but as anything YMMV!!!
I'm pleasantly surprised and impressed.
Edit. Upon further review let me state, I am on 13.1 and the store unit is on 13.0. Also, I will say the colors seem a little more vibrant on my Xs Max, like they're punchier ever so slightly.
Edit #2. My Xs Max has more contrast, like it's sharper more in tune. The Pro Max is ever so slightly fuzzy.