Use APKPure App
Get Not "Running in the background" old version APK for Android
Snooze la notification « App est en arrière-plan » sur Android O
This is a tool that snoozes the "App is Running in the Background" notifications on Android Oreo.
1.Run the app and grant Notification Access permission in system settings.
2.Start the service and manually snooze the "Running in the background" notification once. The app will keep it snoozed afterwards.