Samsung
Allow or Restrict Background Activity of Apps auf Samsung
Background activity lets an app keep running tasks, sync data or refresh content even after you close it. On Samsung devices running One UI, this is controlled per app through the battery settings, not through one global switch.
When several apps run background tasks at the same time, battery drain increases even though the screen stays off. Samsung separates this permission from notification settings or app permissions like location and camera, calling it background activity in the battery menu.
To change it, go to Tap on Settings ➔ Tap on Apps ➔ Choose an App ➔ Tap on Battery ➔ Enable or disable Allow background activity. Turning this off stops the app from running tasks once you leave it, which helps battery life but can delay notifications, message syncing or location updates from that app.
Restricting background activity works best for apps you open occasionally and do not need real-time updates from. For messaging or calendar apps that rely on instant sync, keep background activity enabled and look at other battery settings instead if drain is still an issue.