If i put say 123.123.123.123 into firefox desktop or mobile it will try to load a webpage from that host. If i put http://[ipv6] into desktop it works as well. If i do the same on mobile it sends it to my search engine as a query.
It's only once you visit a website that it matters whether you're on an IPv6 network. OP isn't visiting the website at all; they're just typing the address and being taken to their search engine