“Is dark mode impacting your users”, Maygen Jacques asks in this article about some less-considered aspects of designing for “dark mode” — specifically the impact of fuzzy vision from white text on black background for users with astigmatism:
Let’s assume 25% of your users don’t permanently need glasses but they also get this issue in conditions of low lighting; that’s a total of 50% of your users experiencing a shared issue.
Designing for dark mode is about more than just inverting colours. And real-world testing will always be necessary. Most importantly, it is crucial to allow users control over turning dark mode on and off for a specific website, if the design causes them issues:
The take-home message is - give your users control; make dark mode optional.
On the same topic, also see Bookmark: “Accessibility for People with Astigmatism”.