Notifications on iPhone don't show up anymore.

I'm using an iPhone 12 with iOS 17.5.1.

A few days ago all of my notifications (except for calls) stopped showing up.

The general settings, the app-specific settings as well as the settings within the apps are all correctly set up.

I tried turning the device off and on again. I also tried to force-restart the device.

Nothing works so far. I just don't get any notifications anymore.