Someone else pointed this out to me, if you run an app for a few seconds and then kill it off, the time reported will be 1 minute. If you start 10 apps that same way, it will be reported as 10 minutes. So iOS 15 is definitely over reporting app time used. It is always over reporting app time used to the next minute. I have verified that myself. We already know that iOS 15 is over reporting battery percentage. So I believe what we are seeing in the battery usage charts is over reporting app time used and battery percentage used. Which confirms my suspicion that the battery usage charts are not useful because they are over reported.
My question is, has there been any change in the iOS 15.1 beta that corrects the over reporting of battery usage?
Yes, it's me I think. For the fun, I've just opened 30 different apps in a row (open, close, open, close....) and I have 30 minutes Screen on time !