Zack Hand

You don't need to use the system default screen off feature. You could add a soft mode to show a fully black screen while recording. It avoids wasting battery power by turning off pixels that aren't being watched.

I see no point in adding this feature to Open Camera because it is very easy to install QR/barcode scanner from F-droid.

+1 It is important for saving battery while recording with the camera in a fixed position. When we record ourselves dancing salsa, we place the phone where it can see us and no one looks at the screen while it is recording.