Standby mode going to lock screen then back again

iOS 17.2.1, iPhone 15 Pro, using Standby with an Anker 3 in 1 Magsafe cube. Everything works as it should, until the middle of the night, when all of a sudden the display will light up full blast with my lock screen for a second, and then go back to the dim Standby clock/calendar display. I think it's happening when the phone is fully charged--it stops charging but somehow also thinks it's no longer connected to the Magsafe cube, but then re-connects (I can hear the vibration signifying that it's charging again). Very annoying since it's bright enough to wake me up. This can happen several times during the night.

Anyone else seeing this? Got to be a bug in Standby mode, I would think.