I have Note 9 and had heavy night mode redness. It was due to Google Play Book
I would also check if Google Photos or any other photos app has same behavior
If no luck with above two, try clearing cache (or even storage) from App Manager > Gallery to reset the app settings
I never even had Google books on my phone and it was still the problem, I had to go download it from the play store and do the fix. It worked but how did it happen without ever even having the app in the first place?
Thannkkkk YOUUUUU! This is issue has been driving me nuts forever. I knew some app was to blame but I couldn't figure it out. Like other people, I didn't even have Google Play Book installed so it's a little suspicious than an app that was not even installed could change my settings. Someone should explore that....