Samsung
Manage Sleeping Apps auf Samsung
Samsung phones group apps into background usage categories to save battery. An app marked as sleeping stops running in the background entirely, so it will not update content or send notifications until you open it manually.
This behavior lives inside Battery and device care, not inside the app itself. That is why an app can look fine on the home screen while its notifications quietly stop arriving.
Where sleeping apps are managed
Open Settings ➔ Battery and device care ➔ Battery ➔ Background usage limits. Here you choose between Sleeping apps, Deep sleeping apps, and Never sleeping apps.
To move an app onto one of these lists, open the matching category, tap Add, select one or more apps, and confirm with Add. The apps stay paused until you remove them again.
To reverse this, open the same category, tap the menu icon, choose Edit apps, select the apps you want to release, and tap Remove. They return to normal background behavior right away.
If an app still misbehaves after removing it from these lists, check its individual notification and battery permissions as well, since both systems can restrict background activity independently.