Try these things if they can work for you-
Check for any restrictions: Your iPhone may have restrictions set up that prevent certain apps, including the camera, from working while driving. To check this, go to Settings > Screen Time > Content & Privacy Restrictions > Allowed Apps and make sure the camera app is enabled.
Update your software: Make sure your iPhone and car's software are up to date with the latest updates. Outdated software can cause compatibility issues between the iPhone and the car's entertainment system.
Restart your phone: Try restarting your iPhone by turning it off and on again. This can often fix minor software issues that may be causing the camera to not work.
Reset the CarPlay connection: Unplug your iPhone from the car's USB port and then plug it back in again. If this doesn't work, try resetting the CarPlay connection by going to Settings > General > CarPlay > Your Car > and tapping on the "I" icon to forget the car. Then reconnect your iPhone to the car's USB port.
Check the car's manual: Check the car's manual or contact the manufacturer to see if there are any known issues with CarPlay and the camera on your iPhone model. They may have specific troubleshooting steps or updates available to resolve the issue.