The black screen vanished. The fnf github io page reloaded, looking fresh and normal. The gray link was gone. In its place was a single new entry at the top of the mod list, in bright green text:
GitHub is the primary distribution point for custom engines that expand FNF’s capabilities. These engines are often hosted as repositories that developers can fork to create their own "github.io" sites or standalone mods. FunkinCrew/Funkin: A rhythm game made with HaxeFlixel fnf github io