Why is the total screen time much higher than the sum of the apps?

Hi,

My iPhone 15 Pro shows a much higher screen time than what I get if I manually summarize the time spent for each individual app. In the example attached, the apps sum up to 1h 22min, which seems very accurate for that day. But the phone claims I have used it for 5h 48min!

Every day is like this. It is less wrong on days I use the phone more, but always completely off.

In earlier iOS versions it reported time spent on home screen & locked screen. I don’t know if it is possible to see that anymore. But obviously I haven’t spent 4h 26 minutes on my home screen. On the day in the example, I had the phone to my right laying on the table for the most of the day while attending an 15 hour online seminar. It was in «Do not disturb»-mode, so the always on display was deactivated and the screen completely dark.

The device:

iPhone 15 PRO with iOS 17.3.1

Online I have seen people all the way down to iOS14 have this issue, but I haven’t found any explaination. ChatGPT 4 didn’t have any good answer either.

Other devices: I have an Apple Watch and an iPad, but the iPad wasn’t used that day. I don’t have a Mac.