Why is my new iPhone 16 Pro Max's screen brightness lower than other models?

conmpare the brightness with my iPhone 13, and seem to have the same brightness. Took it outdoor and seem not as bright as my friends iPhone 14 and 16 pro max. Took it back to Apple Store and compare with all demo units in the stores , and show significant lower brightness at max setting. Talk to an apple tech, he could not figure it out and bought another new one 16 pro max 256gb, and have the same screen brightness issue . The apple tech says there is nothing they can do but to refund the phone and admit that Probally a batch issue.

[Re-Titled by Moderator]