I believe this does not need support attention as it is most likely caused by misconfiguration of old vs new cloud service. Thing is that pre-6.43 RouterOS is using old cloud service. If you upgrade your device WITHOUT disabling cloud service first, the entry will be stuck there forever. New version (6.43+) uses new cloud service. If you enable it, it might take precedence over old service, but as far as I know, it does not disable/delete the old service.
There is very clear warning in changelog about disabling /ip cloud before upgrading to 6.43+ . Same goes when downgrading system - disable it before, enable it after.
Not sure though why Mikrotik took this approach but I guess they had some reason. Since 6.43 release, there has been numerous occurences with advice "downgrade, enable'disable cloud, upgrade again" or vice versa from staff. Personally I consider this approach as unnecessary obstacle. Ideally, only last service should be active. If new cloud receive ddns setting, it should automatically disable and delete old cloud setting. And same should happen when old cloud receive ddns setting - it should disable and delete new cloud setting. That way, people can't possibly make a mistake.