locked out for 8 hours

My daughter went to bed last night and woke up to find her iPhone 11 Pro had locked her out for 8 hours. She had not forgotten her passcode nor had she used it at all

over night. She then waited for 6 hours and 22 minutes when the screen froze. She waited to see if it was going to change and it didn’t. After another 10 minutes of a frozen screen, she then turned her phone off then on again and it had locked her out for another 7 hours. She is away camping so not able to get to a computer. Any ideas what is going on or what can do?