Android
Turn Banner Notifications On or Off for Individual Apps auf Android
Banner notifications, also called pop-on-screen alerts, briefly appear at the top of the display when your phone is unlocked. They sit apart from the notification shade and from the lock screen, which is why muting an app there does not always stop the banner.
Each app manages its own banner behavior, and within an app you can go even further and control it per category, for example messages versus promotions in the same app.
To change it, open Tap on Settings ➔ Tap on Notifications ➔ Tap on App notifications ➔ Choose an App. Inside the app, pick Choose a Category if the app splits notifications into types, then use the toggle to Enable or disable Pop on screen.
Turning this off does not silence the app completely. Sound, vibration, and the notification in the shade still work as before, only the on-screen banner disappears.
If you want to mute an app entirely, including sound and shade entries, use the main app notification switch instead of the banner toggle. If banners still show up after disabling them, check whether a second, work or dual-app profile of the same app has its own separate notification settings.