I put a new SIM card in my phone, then took it out and rebooted. Afterwards I noticed the screen brightness was up to nearly 100% (I always have it all the way down). Auto-brightness was off both before and after. Does anyone know why this might happen? Is brightness somehow linked to my Google account (which was invalidated on the phone due to the SIM swap)?
I'm going to assume that, as suggested in the comments, brightness is (for some reason) one of the settings that gets wiped when the SIM is swapped.