Consider the following scenario:
In a Windows Server, version 1903 or Windows Server 2019 environment, you have a Host Guardian Service (HGS) node, a guarded host, and a domain controller (DC) installed.
You verify that the guarded host is working by running Get-HGSClientConfiguration. This cmdlet should return IsHostGuarded as True.
You in-place upgrade the HGS node and the guarded host to Windows Server 2019. To do this, you run Setup.exe from a mounted ISO of Windows Server 2019.
You run Get-HGSClientConfiguration again.
In this scenario, the output of the IsHostGuarded is False.