My personal theory of display ergonomy is that a light background is better for the eyes because then you have to dial down the screen brightness all the way to a level that's good for reading (generally something close to paper white in the same environment, and usually much lower than the display's maximum brightness).
Admittedly this theory is only backed by personal preference and some vague recollections of CRT-era ergonomics discussion in 1990s UI design books.
> Admittedly this theory is only backed by personal preference
Same for my argument too.
There is also the cultural factor. The age when I was going to make a decision about which high school to choose and what kind of study to pursue, we had the chance to enjoy the release of a few of the best sci-fi movies/shows ever made. Those movies had the black screen, neon green/blue strokes and fonts as the main design language. Looking at the letters falling down in the movie Matrix, it was like "coooool, I wanna be able to type those in real time and make computer do stuff".
Lots of us younger people have dark mode with the screen brightness turned way down. I personally often have my screen brightness at minimum, and on mobile I have Extra Dim turned on for more than half of my usage time.
OTOH reading too low-contrast text is supposed to be bad for the eyes too? (At least that was what parents and educators told me as a kid: “Read at your desk where the light is good or you’ll spoil your eyes!”)
And us older folks have screen brightness turned up as our eyes get worse.
For many years I had white background so I could really see things.
Now with floaters I have to use dark background and many games are now unusable as they have light background and medium unreadable text and strain my eyes.
No, it's backed by evidence. Light mode is, objectively, better for your eyes because light characters on a dark background tend to "bloom" and be less clear.
Admittedly this theory is only backed by personal preference and some vague recollections of CRT-era ergonomics discussion in 1990s UI design books.