chrony port 323 automatically open with firewalld?

Documentation states chrony uses port 323udp by default, versus port 123udp that old NTP used. But where is port 323 defined, because I do not see it in the default /etc/chrony.conf as it comes in a clean install of either RHEL-7.9 or RHEL 8.9. Also, in either /etc/firewalld/zones/public.xml which is the default firewall from a clean install, or even in my custom firewall xml file, I do not open either port 123 or port 323 and chrony seems to work - my time is correct the service is successfully running and chronyc tracking reports

A netstat -lun does shows

Biggest question is why is this like this regarding the firewall, since I am pretty sure I did not explicitly open port 323. Where should I look for how port 323udp gets opened with firewalld (in RHEL-7.9) ? And where does chrony explicitly have port number = 323 defined?

/etc/firewalld/zones/public.xml has only this :