How to pause throttling and blocking of out-of-date on-premises Exchange Servers

mashall_khattak I experienced the same after updating to latest CU and ran the cmdlet Get-OnPremServerReportInfo. Apparently it is expected behavior.
As per this article, Throttling and Blocking Email from Persistently Vulnerable Exchange Servers to Exchange Online - Microsoft Community Hub under FAQ:
"We upgraded our servers to an up-to-date version; why doesn’t the reporting reflect that?
The reporting currently doesn’t show servers that comply with the current update version recommendations. In the EAC, once a persistently vulnerable server is brought up to date, the server will no longer appear in the report. In PowerShell, the Get-OnPremServerReportInfo output only includes all of the past detected persistently vulnerable versions for the server(s). It will not include records for the server versions that are currently not considered persistently vulnerable."