How can I ensure accurate screen time tracking on iPad?

Actually i am at boarding school so. I have to submit my ipad at night 10:00

so i power it off and thn submit it to gadget room. And thn at morning i take it around 7:45/7 and thn when i use it for few times in a day. Approximately 25/30 mins a day. When at night i check my screen time it shows 11hrs 12 hrs and the first pickup shows 12:00 am

how can my first pick up be at 12 i already sumbit it at 10 but it shows like that and screen time is always on higher side is this only me or theres the same issue with others also?