While there should not be any stale ports in OVN it can happen due to things like bug #1949943. In this scenario, the Neutron metadata agent will likely find more than 1 port in the same network with the same IP address. However, only one of them will be bound so metadata agent should provide resilience to such scenario by attending only to those. I posted a patch for review to master branch: https://review.opendev.org/c/openstack/neutron/+/787337
Verified that puddle RHOS-16.1-RHEL-8-20210727.n.1 contains python3-networking-ovn-7.3.1-1.20210714143305.4e24f4c.el8ost.noarch which includes the fix.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (Red Hat OpenStack Platform 16.1.7 (Train) bug fix and enhancement advisory), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2021:3762