I never changed / replaced the camera on my phone I suddenly get a message that the camera on my phone may not be genuine.. does anyone else gets this problem?

The same happened to me. This has to be a bug. All of a sudden the message was there. Nothing is wrong with the camera and it hasn’t been altered. No changes to phone or camera.

If you are the original owner of that iPhone 13 Pro and therefore are certain that the camera was never repaired or replaced, then you may have a malfunctioning camera. I recommend that you have your iPhone examined at the Apple Store or at an Authorized Service Center for further diagnosis and a resolution.

Axel F.