There is a race condition if 1 API worker creates a SG and other API worker tries to create a SG rule in the same SG. It could happen that the second one doesn't have yet the NB `ACL` in the local cache.

This issue was reported in the U/S bug https://bugs.launchpad.net/neutron/+bug/2090921, when trying the deploy OpenStack in several servers. In one of the `Port_Groups`, several `ACL` were missing. That was found while executing the `neutron-ovn-db-sync-util` too.