iOS 15.5 - display keeps dimming to 50% even with auto dimming disabled

[Project Alice]

Title pretty much says it all. Is this happening to anyone else?
I have a 2nd gen iPhone SE (2020). It isn’t a heating issue because I can turn the brightness up, but it constantly turns it back down to 50%. It is extremely annoying when I’m in the car or outside where I want it to stay at 100%.
I don’t remember having this problem prior to 15.5; while it did auto dim it would not do it literally 5 seconds after I turned it back up.

 

[asus389]

My 8 Plus is doing this also. I have auto brightness disabled and brightness is manually set to about 80%. However the screen will periodically dim itself for no apparent reason. When it does this, the brightness level doesn’t drop in the slider in control center but the screen does get dimmer. Not sure why it does this, my 6S doesn’t do it. They are both on 15.5.

 

[Bazza1]

iPhone 12 Mini here running 15.5 and I've had this happen from time to time - almost to the point of near blackout, so hard to navigate to Settings > Display and Brightness to check setting there. Sometimes the slider is showing the drop in brightness - sometimes not. In the case of the latter, I've had to do a hard reboot to fix. In the case of the former, no idea what has caused this, and I've simply moved the slider. And it's not set to adjust depending on ambient lighting.

All that said, not limited to current phone or 15, either. I recall this being a (albeit rare) occurrence on earlier devices / iOS, too.

 

[asus389]

Honestly, I think its doing it to manage heat. But it shouldn't be getting hot considering what I'm doing with the device. Most of the time I've just been browsing safari on wifi and it feels a bit warm to the touch. Ambient temps are in the 80s, which is well within the design spec. Are your guys phones warm to the touch when the screen dims?

 

[now i see it]

When the phone gets too hot (according to iOS) the screen is forced to display dimmer. No way to turn it off.