If you are sharing the same Apple Account (formerly Apple ID) with family members or friends, and Share Across Devices is enabled under Screen Time, you may see unusually high or unexpected usage figures.
When the same Apple Account is used on multiple devices and Share Across Devices is enabled, Screen Time can combine usage data from those devices and display it together. As a result, the reported screen time may be much higher than the time you personally spent using your iPhone.
For example, if you use your iPhone for 4 hours and another person using the same Apple Account spends 6 hours on their device, the combined usage may appear as 10 hours, depending on how Screen Time records and displays the activity.
Important: Sharing an Apple Account with other people is not recommended. Each person should use their own Apple Account, and Family Sharing should be used to share eligible subscriptions and other services. This helps keep personal information separate and makes Screen Time reports more meaningful.
To check the setting, go to Settings → Screen Time → Share Across Devices. If you want to see usage for an individual device, turn this option off and check the device-specific report. Keep in mind that this setting controls how usage is combined across your own devices; it does not necessarily mean that activity from every device belonging to another person will be included simply because they share your Apple Account.