on the samsung device we can give an app the permission (appear on top) to show itself over other apps. a well-known example is the messenger of facebook. the chat icons always lay over other apps. if this is not desired, we could disable it in the settings. samsung called the function "Appear on top", different from the usual android function.

Android 10 (One UI 2.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Apps
Step 3:  Open the  menu
Step 4:  Tap on  Special access
Step 5:  Tap on  Appear on top
Step 6:  Enable or disable desired  App
  1. Open the Settings
  2. Tap on Apps
  3. Open the menu
  4. Tap on Special access
  5. Tap on Appear on top
  6. Enable or disable desired App

Samsung Instructions