CNV-42747: Added a note about OCP 4.16

This is an edited version of Oren's original content from PR #86933 and
extended by me based on information kindly provided by him.

modules/virt-preventing-workload-updates-during-control-plane-only-update.adoc

@@ -8,6 +8,26 @@
 
 When you update from one Extended Update Support (EUS) version to the next, you must manually disable automatic workload updates to prevent {VirtProductName} from migrating or evicting workloads during the update process.
 
+[IMPORTANT]
+====
+{product-title} 4.16 upgraded the underlying {op-system-first} system to version 9.4. To operate correctly, all `virt-launcher` pods in the cluster need to use the same version of {op-system}.
+
+After upgrading to {product-title} 4.16 from an earlier version, re-enable workload updates in {VirtProductName} to allow `virt-launcher` pods to update. Before upgrading to the next {product-title} version, verify that all VMIs use up-to-date workloads:
+
+[source,terminal]
+----
+$ oc get kv kubevirt-kubevirt-hyperconverged -o json -n openshift-cnv | jq .status.outdatedVirtualMachineInstanceWorkloads
+0
+----
+
+If the previous command returns a value larger than 0, list all VMIs with outdated `virt-launcher` pods and live migrate them to a new version manually:
+
+[source,terminal]
+----
+$ oc get vmi -A -l kubevirt.io/outdatedLauncherImage=
+----
+====
+
 .Prerequisites
 
 * You are running an EUS version of {product-title} and want to update to the next EUS version. You have not yet updated to the odd-numbered version in between.