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/
Most of China can't reach Google so the reporting is off anyway. But in 2023 the govt mandated ipv6 support to all carriers and manufacturers.
https://www.theregister.com/2023/10/17/china_networking_hardware/