Many iPhone and iPad users have discovered Screen Time is reporting incorrect time estimates for apps and webpages, sometimes showing numbers that are considerably wrong.
Often the incorrect Screen Time reports will be calculated as many hours for websites or web pages that may be opened as a tab in Safari or from another app, or apps that are in the background and not active. Screen Time then erroneously reports the time on screen of the apps or webpages as the iPhone or iPad as being wildly inaccurate, muddying the Screen Time data and making it largely useless.