One of the innovations in Android Oreo - constantly hanging in the notification curtain notification about the operation of background applications. It appears as soon as any application goes into the background, and in principle does not carry any benefit, because you already know what applications you have running.
You can remove this notification using the application "Hide in running the background" Notification.
It is available on the Google Play Store for free, and on GitHub you can find its source code.
Install the application, run it, give it the required permissions, and at the same time the notification about the background work will disappear and will no longer be an anomalous eye. In the curtain of notifications, there will be room for really useful things. The app is only compatible with Android 8. 0 Oreo, because on earlier versions of Android, there is no such problem.
Download for Android.