This is due to the way OLEDs work and it a bad idea for long term use.
Notice a very slight bluish/greenish tint on whites? Thats because the blue OLED pixels fade much more quickly than other colors. Its a well known trick to take a full screen device and tint it ever so slightly depending on the OLED per-color lifespans. That way your device is acceptable when you first get it (all colors are "fresh",) colors degrade and actually become more balanced over a certain amount of "usage time," and by the time it is noticeable that your blue pixels are fading, you're on to a new device already.
I don't know what the "aging time" for each color is (other than that blue dies more quickly and was a big hurdle in getting OLEDs to the market,) nor do I know how much they compensate when assembling the screen, or the targeted "on time" for a "balanced" screen. If you run your entire screen with a red tint for say, 70% of its use, you could potentially burn out colors prematurely and make your screen look wonky.
Honestly if I could get a huge battery boost by running in nighttime mode I'd have no issue with a color tint, but I wouldn't want my screen looking oddly pale due to dieing reds in a year so I'll personally be avoiding this.
tldr;
each pixel color has its own "lifetime"
use lots of one color instead of the other and you'll age those pixels more quickly
when all your reds are aged more compared to the other colors, things will start to look funny when you operate without a screen tint.