My 11yo goes to bed at 9-9.30..but is often awake long after that. He can be up before 7.30 but sometimes needs waking. I think this is a usual behaviour for the age. Not quite a sleepy teen, no longer a child!
Ds (11) goes to bed around 9.30, gets up between 6.30 and 7.30. Have no idea when he goes to sleep, I don't check on him. My take is that you can police bedtimes but not what time somebody is asleep, and that you can rest while lying awake in bed.
Ds has always needed less sleep than his sister who is 3 years older.