There as absolutely no reason for anyone in Arch to use snap to install something mainstream like Firefox. Same goes for other OS’s like Fedora etc. (which are all mined in similar way, just change it to /fedora for instance).
The page presents itself as if it’s the only choice, and can easily scam someone who’s just getting into Linux into installing snap. I think it’s designed for that purpose. Arch links to the package, but not step by step guide (which is on Arch), but this can easily lure people into installing snap and being none the wiser the it’s not the default package manager for their distro.
It’s 4th for Firefox, but I’ve seen it as the top result for some other packages. Probably Google caught up, or probably for packages not mainstream as Firefox it still shows snap as number one result.