Oppo
Allow or Restrict Background App Activity auf Oppo
ColorOS ships with an aggressive battery optimization layer on top of Android. Part of that layer is the background activity control for every installed app.
When background activity is disabled, ColorOS decides on its own when an app is allowed to run without being open on screen. In practice this often means the system freezes the app the moment you leave it, which stops push notifications, delays message delivery, and interrupts location or fitness tracking.
You find the setting per app under Tap on Settings ➔ Tap on App management ➔ Tap on App list ➔ Choose an App ➔ Tap on Battery usage ➔ Enable or disable Allow background activity ➔ Tap on Allow.
Enable the toggle for apps you rely on for real-time alerts, such as chat or navigation apps. Leave it disabled for apps you rarely use, since that keeps battery drain lower without affecting apps you actually need running in the background.
If notifications still arrive late after enabling the toggle, check whether the app is also restricted in a separate power-saving list, since some ColorOS versions manage background permissions and battery saver exceptions independently.