I do not understand why on my dynamic DNS service 'rjcahome.dynuddns.com' the system only update automaticly the ipv6 and do not update the ipv4.

It is a Raspberry Pi 5 who is updating the system.

An example of IP Update History where you can see the ipv6 it is upadated but the ipv4 does not appear.

024/06/01 01:07:58 /nic/update?hostname=rjcahome.dynuddns.com&password=***** No Change
2001:08a0:7bd6:de00:69db:4661:233c:7b02 curl/8.1.2