I have "Open tabs in links instead of new windows" checked. I have no plug-ins that would cause this. I have experimented with the various, conflicting "about:config" directions given online. (Nothing works, so I have reset about:config to default.) *It is also worth noting the Firefox Support page is immune to its own Dark mode. WHY. I am going to switch to Opera, since it has none of these problems. Before commenting or responding on this post, make sure you actually READ IT first. I am so tired of these online MANSPLAINERS being all, "Go to about:config and do blah-blah-blah," or, "This is what you do: Go to Settings > General > Tabs > make sure you check the box that says "Open tabs in links instead of new windows." Seriously, way too many people online are like customer support agents on the phone: "Try unplugging it and wait 15 seconds, then plug it back in; try closing it and restarting it." If anyone has any real solution, I'd greatly appreciate it.