Is the lens of the camera clean? A dirty lens can cause focus issues. Does it occur in Safe Mode?
To enter Safe Mode:
While in Safe Mode, your phone will only have access to core apps that were pre-installed in the phone at the factory.
1. To activate Safe Mode, hold the power key until the Power off icon appears.
2. Press and hold the Power off icon until the Safe Mode prompt appears.
3. Select Safe Mode to confirm.
Once your device has powered on, you should see the words "Safe Mode" in the lower right/left corner of your screen.