@nprofile1q... @nprofile1q... https://www.rfc-editor.org/rfc/rfc4291.html#section-2.5.5.1 says those addresses are deprecated, and "new or updated implementations are not required to support", also RFC5156 says "these addresses are deprecated and should not appear on the public internet". The `::ffff:ipv4` form does work with musl though (and this form isn't deprecated). I don't know why they deprecated the nicer looking one...
Although musl does fail one of sortix's https://gitlab.com/sortix/os-test/-/blob/main/basic/arpa_inet/inet_ntop.c the '::89ab..' has some extra '0:0:'.
Thought about adding a new test case there, but since this form is deprecated it probably doesn't matter what the output looks like.