iPhone 13 lock screen staying randomly on at a dim brightness without clock?!?

Hello, I have an iPhone 13 (so no Always-On option) and I am charging it at night every day. Also I use do not disturb. Lately when I wake up in the middle of the night I find my screen turned on at very dim brightness on the lock screen, but without the clock! I could say it's a little creepy seeing it like that😅. Is this a fault? Is there anything I can change in the settings? Thanks!