inetutils' ping program uses ipv4 for pinging by default even when an ipv6 address exists for the host. i consider this a bug because ipv4 is the legacy IP protocol so it should not be the default. ipv6 should be used over ipv4 whenever possible.
ping is for IPv4, ping5 is for IPv6. There is nothing "legacy" about IPv4. Use the right command for the right task.
