Documentation Error

Traefik Docker Documentation | Traefik | v3.0

IPv4 && IPv6
When using a docker stack that uses IPv6, Traefik will use the IPv4 container IP before its IPv6 counterpart. Therefore, on an IPv6 Docker stack, Traefik will use the IPv6 container IP.

Does it use IPv4 or IPv6?

Probably better to open a Github issue.