Etcd was in degraded state with following error during the upgrade from 4.17.37 to 4.18.25 : 

~~~
etcd                                       4.17.37   True        False         True       352d    RevisionControllerDegraded: unable to ApplyStatus for operator using fieldManager "etcd-RevisionController": Etcd.operator.openshift.io "cluster" is invalid: status.latestAvailableRevision: Invalid value: "integer": must only increase
~~~    

 4.17.37  

We are not able to reproduce in our cluster.    

The following Jira describes the similar issue with `kube-apiserver` component which has been fixed in 4.19 and backported to 4.18.
- https://issues.redhat.com/browse/OCPBUGS-48276

Etcd was in degraded state with following error : 

etcd                                       4.17.37   True        False         True       352d    RevisionControllerDegraded: unable to ApplyStatus for operator using fieldManager "etcd-RevisionController": Etcd.operator.openshift.io "cluster" is invalid: status.latestAvailableRevision: Invalid value: "integer": must only increase

We outlined the similar issue mentioned in BUG [1], component is etcd. 

By using below command it resolved the issue :

$ oc -n openshift-etcd annotate configmap revision-status-13 \
operator.openshift.io/revision-ready=true --overwrite

[1] https://issues.redhat.com/browse/OCPBUGS-58412