If you are receiving YouTube notifications on your iPhone 11 but not on your iPhone 16, the issue may be related to the Focus settings. Each iPhone can have its own Focus configuration, and unless you enable “Share Across Devices” under Focus, the settings won’t automatically sync between your iPhones. This means your iPhone 16 could be filtering or silencing notifications while your iPhone 11 is not.
Additionally, make sure you are signed in to the same YouTube account on both devices. YouTube notifications are tied to the Google account being used, not the Apple ID. Even if you are using the same Apple ID across devices, the YouTube app’s notification preferences must be checked and configured separately on each iPhone.
Lastly, notification settings do not carry over automatically from one device to another.