Hello, StanCoffin. Thank you for posting your question to the Apple Support Communities. You’ve come to the right place to get help with using the Screen Time features of your iPhone.
From what we gather, you are seeing Screen Time reported for an app that you do not have installed on your iPhone. App usage like this may be shown for several reasons and we would be happy to help you find out more.
As it turns out, Screen Time includes a feature known as “Share Across Devices”. With this option enabled, your app usage from any devices that are attached to your iCloud account will be shown when you view your Screen Time usage.
Do you have this same app installed on any other devices that you regularly use?
You can also find more information about these features in the following Apple Support article:
Use Screen Time on your iPhone, iPad, or iPod touch - Apple Support
If you do not have this app installed on any other devices and would like more help, we would suggest contacting Apple Support directly to continue. Depending on your current location, you may be able to contact Apple Support using the following link:
Get Support
We hope that this information helps you get the most from the Screen Time features of your device.
Cheers!