The iOS 16.5.1 (c) can fix the front camera due to not working

If you still need help, reset your Face ID, then set it up again. Go to Settings, tap Face ID & Passcode, then tap Reset Face ID. Next, tap Set up Face ID to set it up again.

If Face ID isn't working on your iPhone or iPad Pro

Anyone who has their iPhone Camera replaced/repaired/serviced by an unauthorized service provider will have this warning message.

• They will see an Unknown Part  message if the camera installation is incomplete or if the camera:

1. Was replaced with a nongenuine camera
2. Was already used or installed on another iPhone
3. Isn't functioning as expected
4. This message doesn't affect your ability to use your iPhone or access your camera.

Parts and service history

With iOS 15.2 and later and iPhone XR, iPhone XS models, and later—including iPhone SE (2nd and 3rd generation)—you can go to Settings > General > About for the parts and service history of your iPhone. You can also find out if the battery has been replaced. If the replacement was done using genuine Apple parts and processes, "Genuine Apple Part" will appear next to Battery.

If your iPhone's camera has been previously replaced, repaired, or serviced by an unauthorized service provider, it's worth noting that Apple may decline to provide service for your device. The decision to refuse service will depend on the specific components that were affected by the unauthorized service.

Get a Genius Bar Reservation and Apple Support Options - Apple

Contact Genius Bar.

Manage Reservations - My Reservations - Apple