It's not about scientific anything for me, it's just less strain and more comfortable on my eyes. And if you have an OLED display, it will preserve battery life too...
It’s a placebo really, one easily addressed by having a good light sensor to adjust auto brightness.
It’s 1:45 in the morning as I type this on a perfectly white but low brightness background because my youngest was having a nightmare.
It’s not straining on the eyes at all. Dark mode on the other hand would make it hard to read what I’m typing in the same low light environment.
Battery life? Sure but it’s a paper value and really not worth it for what is ultimately worse for your eyes.
Furthermore, as someone with serious astigmatism it’s basically impossible to use as all the text is constantly moving and shaking in dark mode.
Flipping between those two, yes sure it seems like the white may be more straining at first glance until you actually read the words and realise how much easier to read the text is when it’s the contrast of black on white.
Dark mode fails at contrast which is what you need for less eye strain.
In a perfect world dark mode would have been adjusting the white to a similar tone of grey as the background of the keyboard, rather than making it all black.
The True Tone display that keeps the contrast constant and Night Shift that warms up the colour at night is really all you need.