Duckdns ipv6 ddns how?

I've researched some but even their documentation doesn't have ipv6, I don't ask AI for this stuff anymore but, is ipv6 possible with duckdns? My /etc/config/ddns for that is basically this. But it says "never verify" on last update. What does that even mean? I don't understand.
/etc/config/ddns:

config service 'duckdns6'
        option enabled '1'
        option lookup_host 'testtest.duckdns.org'
        option use_ipv6 '1'
        option service_name 'duckdns.org'
        option domain 'testtest.duckdns.org'
        option username 'testtest'
        option password 'some-stuff'
        option use_https '1'
        option cacert '/etc/ssl/certs/ca-bundle.pem'
        option ip_source 'network'
        option ip_network 'wan'
        option interface 'wan'
        option use_syslog '2'

on duckdns site it looks like this:

Yes, however:

probably wrong file?

probably wrong interface?