Grey Area on the Screen Time Graph

Hello,

My screen time on my iPhone has gone crazy for a little less than a week now and I have no idea what is causing this. You can clearly see which app I used the most, how long I've used it, and that it does not match with the overall screen time of the day. What makes the screen time so long are those grey areas that essentially appear during the night (on the first pics) but also at some random times of the day (on the last pics). So I was wondering what were those grey areas and how I could not have them included in my screen time.

PS: I checked and these screen time reports are only for my iPhone, I did not select "All Devices".

Thank you!