Hello domenico28,
We'd like to help with the issue you're experiencing with your iPhone's camera. We understand the rear camera is not working properly.
To confirm, are you experiencing this issue in multiple apps where you use the rear camera?
If so, have you tried restarting your device since this issue began? If not, use these steps to restart your device: Restart your iPhone
You can also check here for additional steps to take if the issue persists: If the camera or flash on your iPhone, iPad, or iPod touch isn't working
We hope this helps!