Hi @royle1 Have you checked permissions? Go to settings-Privacy-ensure Camera Access is toggled on for apps which have Permissions. May need to clear the camera's cache, Go to Apps-Camera - Force Stop- storage- Clear the cache and Data.
However if not resolved would suggest wiping the cache Partition, temporary files will be deleted but no Data is lost.
Follow these steps:
1. Turn off the device.
2. Connect To Computer or plug in USB-C Headphones , Press and hold the Volume Up key and then press and hold the Power key
3. When the Android logo displays, release all three keys.
4. An 'Installing system update' message will show for 30 - 60 seconds before the Android system recovery menu options appear.
5. Press the Volume down key several times to highlight wipe cache partition.
6. Press Power key to select.
7. Press the Volume down key to highlight yes, them and press the Power key to select.
8. When the wipe cache partition is complete, Reboot system now is highlighted.
9. Press the Power key to restart the device.
You can also Repair Apps from the same Recovery Menu.
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 5.0,Android 13 .
@royle1: It is also possible that you have enabled Colour Inversion. If the steps above don't resolve your issue then please try heading to Settings > Accessibility > Visibility enhancements > Colour inversion, and toggle this feature off.