What it means
IPv6 can provide native addressing without some address-sharing workarounds. It has its own routing and firewall configuration and should be tested as a separate path.
For hosting
Protect IPv6 listeners as deliberately as IPv4 ones. Publishing an AAAA record should follow a working application and TLS test over IPv6.
Have you tested the IPv6 path separately?
Check DNS, routing, application listeners and firewall rules. A working IPv4 service can still have an exposed or broken IPv6 route.