[fdr]

There is such a prefix, though, but the problem is the end user devices themselves (or a few applications) are not always modern enough to have decent operation with a IPv6 stack. Less so these days, though. See https://en.wikipedia.org/wiki/IPv6_transition_mechanism, ::ffff:0:0:0/96.

That said, a lot of posts here don't seem to reckon with the fact that a slim majority of www.google.com connections in the United States are via IPv6, and a super-majority from India, Germany, and France. Comcast, T-Mobile, Verizon, as far as I have experienced, these all default to IPv6. While dropping IPv4 support is both a worthy, distant goal and sometimes used in goal-post moving rhetoric, it's not like nobody uses IPv6...rather, mobile broadband networks have depended on it for over a decade (see T-Mobile's deployment of 464XLAT)