iphone 12pm auto dimming in the sun when auto dim is off

it’s so frustrating. my phone randomly darkens, and i’ve brought it into t mobile before and they have no clue either because all of the settings are off for the auto dimming. i’ve had the phone for 2 years now and it’s done it since it was brand new.

it’s does it when it’s not in direct sunlight either. i have some indirect sunlight in my room and it just autodimmed again while i’m watching a show, and the screen is almost black and i can’t see the show at all.