When it comes to backing up your iPhone through iTunes or iCloud, it's important to note that the actual app files aren't stored in the backup. Instead, what gets backed up are the essential app data and the references or links to those apps in the App Store.
This means that when you restore your iPhone from a backup, the apps themselves aren't directly reinstated from the backup file. Rather, the backup contains information about the apps you had installed and their associated data. During the restoration process, your iPhone uses this information to re-download the apps from the App Store.
This distinction is crucial because it means that while your app data and settings will be restored, the actual app files aren't saved within the backup itself. As a result, a reliable internet connection is necessary during the restoration process to reacquire the apps from the App Store.
This approach helps in keeping the backup size manageable while ensuring that your essential app data and configurations are securely stored and retrievable during the restoration process.