Sometimes my screen will dim for no reason although I have it set at full brightness. The setting shows full brightness but the screen suddenly dims. Used to happen in iOS 12.3 and still happens in 12.4. It also happens on my iPad.
iPhone X
It happens when the device is getting too hot. It's a built-in controller that protects the internals of the phone.
Removing the case may help cause the iPone will cool down faster. Every case (even Apple's) prevent it from cooling, because Apple advices to charge it with a case off.
It's a great idea to bring your device to Apple for diagnostics.
@M_Kichline The steps here worked for me:
https://discussions.apple.com/thread/250526411?answerId=251008421022#251008421022
Only the 12.9 iPad was affected in my set of devices: https://discussions.apple.com/thread/250526411?answerId=251073046022#251073046022
Is it just before the phone auto locks and brightens when you tap?
Normal.
No, it has nothing to do with auto-locking. It can occur at any time during use of the phone. I can’t tie it to any specific event. I play a find-the-hidden-object game that has dark areas so I turn up the brightness for it, and I expect the brightness to stay as set. But the screen will dim unexpectedly when I’m using it or any other app. However if I check the settings on my phone, the indicator shows full brightness, not that the phone has dimmed (even though I know the display is dimmer than it should be). I haven’t been able to determine a specific time that this happens. I can be sitting in one spot where the ambient lighting hasn’t changed but the screen will dim markedly without me telling it to, and if I try to change it back, the indicator shows full brightness, and any attempt to make screen brighter will fail. This also happened in iOS 12.3.4 and at least one earlier version of iOS. Thanks!
I’ll check for that, because that’s possible. I’ve noticed my phone getting pretty warm at times. If I remove the case, do you think that will help? Also, I don’t have a case on my iPad, but I’m pretty sure the dimming has happened on it, too.
Screen dims when it’s set at full brightness
