This was my first dark mode: https://www.dosforum.de/viewtopic.php?t=12253
Been there, done that. A black background is generally more tiring for the eyes. A black background means less light. Less light means the eye's aperture has to open wider. A wider aperture means less depth of field. Less depth of field means the eye has to work harder to focus. There are reasons for using a black background on a mobile phone, as it can save energy. But for any device that has a power adapter, a black background is simply self-flagellation.
It depends on the environment. Of course, reading HN in a dark room will never be pleasant. But looking into a bright white flashlight can really hurt. Good dark modes are not simply black/white but make use of the right font weight and color to reduce glare.
