Greg Thiemonge writes in RHOSPDOC-2197: 

I think that this networkAttachment [see code snippet below] should also be included in the OVN CR of the deployment guide:

https://docs.redhat.com/en/documentation/red_hat_openstack_services_on_openshift/18.0/html/deploying_red_hat_openstack_services_on_openshift/assembly_creating-the-control-plane#proc_creating-the-control-plane_controlplane

(see the section about OVN and the complete example in 4.3)

but maybe we need to confirm it with the neutron squad first.

spec:
   ovn:
     template:
       ovnController:
         networkAttachment: tenant
         ...