Thanks bro, appreciate it. I think Oneplus forgot to inform phone case manufacturers about their inclusion of a very narrow ambient light sensor to the right and slightly below the speaker grille of the 8T.
You can see it if you look at it at an angle under sunlight. Also, I think nillkin's CP+ pro TGSP is the only full bordered one to take into consideration the sensor as seen below:
But the good thing is Oneplus went over and beyond and included
2 ambient light sensors
this time, the other one being the flicker detection sensor moonlighting as ambient light sensor at the back.
So you should see minimal impacts on auto brightness adjustments even though the supcase partially covers the sensor.