That is really a nightmare, it took me 2 hours... Try to use a photo editor tool (I used the one built into Windows Photos) and increase/decrease the brightness manually. Keep trying and eventually it will work.Anyone knows how to fix the PHOTO Brightness issues? I keep trying uploading different versions of the e-photo but still doesn't meet the requirement. SOS.
FYI: the photo taken is bright as it's done by a professional photographer. It's just that after uploading to the portal it turns into black and white and then an error message showed up saying that "the photo is not bright enough".