Dynamic DNS client updates using a private IP address when it cannot determine the public IP address
Under some conditions the dyndns up client can send a private IP address even though 'Use public IP' is set.
Nov 24 01:01:31 fw1 php: rc.dyndns.update: phpDynDNS: updating cache file /conf/dyndns_wan_rfc2136_'my.dyndns.name'_ns1.netgate.com.cache: 192.168.1.5
That firewall is behind NAT and should never send it's local interface IP.
That was tested in the current 22.01 snapshot at the time but we have seen it in AWS in recent snaps.