This error message is usually seen with some older devices - ie: S6.
It's a Samsung system app - Diagnostic Monitoring Agent = DiagMonAgent. It's annoying but:
You don't need to worry about it & you can either disable it with adb commands or (simpler) Ice Box from the Play Store (costs a couple of bucks) - Or you could always Root the device & uninstall it... Your call 🤙🐧
