Brief: When non-nil use red/blue color-coding instead of red/green,
where appropriate.
Symbol: modus-themes-deuteranopia (‘boolean’ type)
Possible values:
nil (default)
t
This is to account for red-green color deficiency, also know as deuteranopia and variants. It applies to all contexts where there can be a color-coded distinction between failure or success, a to-do or done state, a mark for deletion versus a mark for selection (e.g. in Dired), current and lazily highlighted search matches, removed lines in diffs as opposed to added ones, and so on.
Note that this does not change all colors throughout the active theme, but only applies to cases that have color-coding significance. For example, regular code syntax highlighting is not affected. There is no such need because of the themes’ overarching commitment to the highest legibility standard, which ensures that text is readable regardless of hue, as well as the predominance of colors on the blue-cyan-magenta-purple side of the spectrum.