Mixed-version Cloud Pod Architecture environments are supported beginning with Horizon 7 version 7.4. For example, a pod federation can include pods that are running Horizon 7 version 7.4 and pods that are running Horizon 6 version 6.x.
New features do not work in a mixed-version environment. For example, a new feature that is visible in Horizon Administrator for a Horizon 7 version 7.4 Connection Server instance is not visible in Horizon Administrator for a Horizon 6 version 6.x Connection Server instance. VMware recommends that you upgrade all pods to the same Horizon 7 version.