There is a qualitative difference between your examples and “blacklist”. Dark mode is about color. The color black is a color. Light mode is a color’s brightness. A widely used white background is a color. I don’t think any reasonable person objects to using terms about color to refer to colors. Black objects are black, red objects are red, etc.

But “blacklist” is entirely different. “Blacklist” uses a color term to describe the acceptability of something. It relates a value judgment to a color. I don’t know the history of the term, but I can easily see how it could be at least somewhat offensive.

None of this is to say that the term “blacklist” is problematic or should be discouraged, but your argument about it doesn’t hold water.