I have an iPhone SE and every so often if I'm on it not TOO long the screen will darken and brightness controls don't work. Anyone know?

I have an iPhone SE and every so often if I'm on it not TOO long the screen will darken and brightness controls don't work. Anyone know? - 1

Your phone is overheating and needs to cool down. It's cutting off the backlight to cool it down faster.

You probably are using auto brightness & that could be the cause. Though usually even then you could adjust the brightness.