Dim iPhone Screen After Updating to iOS 10.2.1

[BiscuitAlex]

I've had that happen when the phone was getting too hot and it was trying to protect itself. (I'd stupidly left it on a heating vent.) Once I moved it and cooled it down, it went back to normal.

Anything like that?

Hey I just searched this because it happened and I am noticing my phone is hot. I think this is the reason

 

[AdrianArnold]

I currently have the iPhone X and it was doing this for my 7 and now this phone

 

[andro_l]

After updating to iOS 10.2.1 I have noticed that my iPhone screen gets very dim. I check and I have brightness turned all the way up. Is this a new feature in the update or a bug that needs to be fixed?

settings/general/accessibility/Display Accommodations /Reduce White Point -->OFF

After upgrading my iPhone SE to 11.2.2 I had the same problem. very dim screen even when fully charged. with previous IOS version i never had my phone on more than 50% brightness and after upgrade had to have it up to 100%... auto brightness is always off in my settings. I was trying to figure out a reason for that and found that settings/general/accessibility/Display Accommodations has two options: auto-brightness (which was off) and Reduce White Point option with a slider that was at 80%. sliding down to 25% (lowest possible) or turning this off solved the problem.
Reduce White Point apparently reduces intensity of bright colours - aka dims your screen 30-50%. So, turn it off and enjoy your phone. Andro