Context:
People have been asking for IPv6 Support on GitHub since years (probably a decade by now)
… and someone even got so annoyed that they decided to setup a dedicated website for checking this: https://isgithubipv6.live/
Just because you have a IPv6 address doesn’t mean you’re actually using it. At best you’re tunnelling IPv4 traffic through your carrier’s IPv6 network. Current estimates (from Cloudflare) show only about 34% of the global internet uses IPv6.
If you only used IPv6, you wouldn’t be able to access nearly 66% of the internet.