You can adjust the tint settings in Common Event 102: Day/Night System. There's an existing formula in there to make the tint change per in-game minute, but you can adjust it to your own screen tint by changing the variables.
To turn it off in specific maps, you'll need to make a Conditional Branch with a Switch on the tint settings Common Event, so the screen tint parts of the event are only active when that Switch is on.
Do you remember exactly wchich setting or variable in your demo was about tinting? I just copied it to my game but there's too many variables I don't want to broke the game.
The variables in the demo project are balanced out as an equation so you'll need to change a few of them. Try adjusting them in a vanilla version of the demo before adding them to your game, just in case.
