Could you send the current VyOS “dns dynamic” configuration and
cat /run/ddclient/ddclient.conf ?
And working configuration for 3.10+
In any way we are working on integration " bookworm", it uses ddclient (3.10.0-2)
Do you use option ipv6-enable if it is IPv6 address?
set service dns dynamic interface eth2 ipv6-enable
+1 solution with update script Dynamic dns didn't supr ipv6 ip address assign - #5 by echowings