Not sure if you looked at the iPhone 11 & 11 Pro phones on the Apple Store display but if so they are running a specific iOS version where the brightness is not as bright in order to avoid screen burning, etc.
I am suspecting also that their color calibration / white balance is different from this specific iOS version as they usually all look whiter than any phone freshly sold and coming out of the box: saw this overtime with whatever iPhone I bought and then compare.
I believe the best and real test would be to compare different iPhones but same model coming from a Store or from different stores.
From my experience I was able to see and beside some small white point variances that all iPhone 11 Pro screens are just warmer than previous iPhone generation ones and this could be just by design so to limit the blue light but indeed uneven screens is a real issue.
I believe it. but I'm just saying even in light of all that, color profile voodoo, I still saw it being yellow across multiple demo units in a store that had glass panes and sunlight coming through. Not sure its as easy to spot in those boxed in Apple Stores, even if it was yellow, especially because of the reasons you mentioned