OK, when I first turn phone on the brightness setting is at about 25% instead of about 80% like I usually have it. Even during the course of the day, it will revert back to 25% brightness for no apparent reason. From what I've read...this isn't an unknown issue.
Do you use Auto Brightness? If so, turn it off in the Settings app, in General - Accessibility - Display Accomodations - Auto-Brightness.
In Settings - Display & Brightness set the slider the way you prefer it.
OK thanks AJ, the auto brightness was ON. I actually looked for something like that, but never could find the correct "maze" of paths to find it. General...then accessibility? really? Lol. Thanks again.