I just discovered something. This could be the cause of dimming issue on 3rd party camera apps and the solution might be simple.
The first picture uses footej camera app with stabilization on.
The second picture uses footej camera app with stabilization off.
Maybe stabilization has something to do with the dimming issue found on camera apps like instagram, snapchat and video calling apps like messenger, skype, etc.
Maybe by default, stabilization is on on these apps and can be disabled on the next update.
The difference is most notable when capturing on dark areas and almost unnoticeable on broad daylight.
Hope this post helps.