Screen time/app limits not working

I have set up screen time and app limits on my child’s phone. But they don’t seem to be working correctly. For example, I have set a 2 hour limit on games. But then when I check his screen time for Roblox it says he was on 4 hrs and 9 minutes yesterday. I know he wasn’t on it that long. He says he’s never gotten an alert that his time was almost up. It also shows his total screen time for the day as 5 hours which isn’t possible because we weren’t even home that amount of time for him to possibly have been on his phone that long. It also shows he was on Facebook for 1 minute, and he doesn’t even have that app downloaded on his phone. And he can’t download new apps without my password. Also, if I look at his screen time on my phone vs what his phone says, the times are different. What is going on with this?