Make sure you have turn on the auto flash in the device.
Please follow the below mentioned steps in order to resolve the issue:-
1) Clear the Cache of the camera (setting>>apps>>camera>>storage>>clear data and cache).
2) Perform the reset camera settings (Open camera app> Camera settings >reset setting).
3) Run the device in safe mode and check the issue.
For further assistance, register your concern in Samsung members app (click on “+“icon>send feedback>Error report/ Ask Questions).
Team Samsung Members