Migrating from OpenshiftSDN to OVN-Kubernetes is stuck and cluster is completely degraded

Issue

• Migration from OpenshiftSDN to OVN-Kubernetes is completely stuck and some nodes are still on OpenshiftSDN network, even though the migration was being done following the official documented procedure.
• Cluster is degraded with nothing being rolled out and all nodes in NotReady state posting errors such:

container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:Network plugin returns error: No CNI configuration file in /etc/kubernetes/cni/net.d/. Has your network provider started?

• Rebooting nodes doesn't change anything and machine config operator is not working, even if following the example from similar article.
• Unknown if multus daemonset has rolled out or not, because pods are not starting as they need cluster network.
• All ovnkube-node pods are in error or CrashLoopBackOff state.