When using dark reader as the most popular plugin for any browser, but we can not read text in all blue buttons in Manjaro website https://docs.manjaro.org
Firefox and other any based Chromium with the plugin dark reader show the same issue.
That sounds like an issue with using dark mode on a site that does not implement it.
Usually happens when a website hardcodes colors.
I appreciate you reporting a bug, but even after you read how to report bugs, you still open a post in the forum besides manjaro does not develop dark reader, so its not a bug is a feature request.