[GoblinSlayer]

>github.io does have an IPv6 address

Are you sure? I don't see it.

Name: github.io

Addresses: 185.199.111.153 185.199.110.153 185.199.108.153 185.199.109.153

[strenholme]

github.io doesn’t have an IPv6 address. {name}.github.io does, e.g. mats-winther.github.io resolves to 2606:50c0:8001::153: