Hi Sofio1724,
Thanks for reaching out here in the Apple Support Communities. We understand you're seeing 'Camera Audio' as the leading cause of battery usage on your iPhone, and we'd be happy to help.
To start, this usage could be due to apps accessing the Camera in the background, or a setting that isn't working correctly. To take a look at what apps may be utilizing your camera in the background, go into Settings > Privacy > Camera. From there you should see a list of apps that have permission to use your iPhone camera. Check here for more details: About privacy and Location Services in iOS and iPadOS
Also, when things don't appear to be working as they should, a restart using “slide to power off” is another great step. Check out this resource for help: Restart your iPhone
If you still see this issue after restarting, be sure that your iOS is up-to-date, and check your battery settings as described in these resources:
Take Care.