The VM can’t be downgraded to the previous version because it has never been upgraded.
It is not possible to downgrade the VM because it has never been upgraded.
The VM has had to be upgraded one or more times previously to allow executing a Downgrade.
It is not possible to perform more than one consecutive downgrade. Once a downgrade has been performed, it will not be possible to perform this operation again until the VM is upgraded again.
Note: The downgrade will be made to the version in which this VM was before the last upgrade, which does not necessarily have to be a number less than the current one.
E.g. VM v.5 → "Upgrade to latest" (catalog version v.10) → "Downgrade to previous" → v.5 (not v.9)