iPhone XS screen dim at max brightness with auto brightness off

I’ve had my iPhone XS for less than a month. The screen brightness was perfectly fine until yesterday. Now, it’s very dim at max brightness. The only time the brightness flickers back on is when I take a screenshot. Anyone else having this issue? My auto brightness has been off since the first day I got the phone. I turned my phone off/on, toggled my auto brightness off/on and still not back to normal. I think I might have to switch it out with a new one.