iPhone XS Max brightness issues

I have had an iPhone XS Max since it released and never had any issues with it until recently. I’m not sure if it’s an update problem but my screen brightness seems to be having issues all of a sudden. When I first unlock my phone the screen will be so dark you can barely see anything (brightness all the way down) then it will suddenly jump from lowest brightness to highest brightness. It’s not a gradual increase like the phone is adjusting to the brightness of the room. It just jumps from dark to bright. Sometimes it takes it several seconds to brighten so I’m left with a dark screen for a moment. It’s not an auto brightness problem either because it still does it even with that setting turned off. Is this a hardware problem or a software problem?? Please help!