Not a blocker, because the alert landed as critical in 4.6 [1], and we don't want to delay 4.7's GA on something that is not a 4.6->4.7 regression.

[1]: https://github.com/openshift/cluster-version-operator/blob/94358e80fa8151e43690d5925abc9337e90dca1c/install/0000_90_cluster-version-operator_02_servicemonitor.yaml#L47-L53

Verified with 4.7.0-0.nightly-2021-03-10-202622

Steps to verify:

1. Install a cluster with 4.7.0-0.nightly-2021-03-10-202622
2. After 1 hour, check CannotRetrieveUpdates alert

[root@preserve-yangyangmerrn-1 tmp]# token=`oc -n openshift-monitoring sa get-token prometheus-k8s` 
[root@preserve-yangyangmerrn-1 tmp]# curl -s -k -H "Authorization: Bearer $token" https://prometheus-k8s-openshift-monitoring.apps.yangyang0311.qe.gcp.devcluster.openshift.com/api/v1/alerts | jq '.data.alerts[]|select(.labels.alertname == "CannotRetrieveUpdates")'
{
  "labels": {
    "alertname": "CannotRetrieveUpdates",
    "endpoint": "metrics",
    "instance": "10.0.0.3:9099",
    "job": "cluster-version-operator",
    "namespace": "openshift-cluster-version",
    "pod": "cluster-version-operator-58cfdd7895-zgdrm",
    "service": "cluster-version-operator",
    "severity": "warning"        <------ severity is changed to warning
  },
  "annotations": {
    "message": "Cluster version operator has not retrieved updates in 1h 6m 4s. Failure reason VersionNotFound .  For more information refer to https://console-openshift-console.apps.yangyang0311.qe.gcp.devcluster.openshift.com/settings/cluster/."
  },
  "state": "firing",
  "activeAt": "2021-03-11T05:45:16.457044785Z",
  "value": "3.964457000017166e+03"
}

Moving it to verified state.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (OpenShift Container Platform 4.7.3 bug fix update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2021:0821