Symptoms
In Control Panel, the Add/Remove Programs item doesn't display the updated Microsoft Exchange Server version after you apply a security update. This issue occurs because the registry value at the corresponding path is updated incorrectly during the installation.
Resolution
To fix this issue, install one of the following updates:
Cumulative Update 11 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019
Cumulative Update 22 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016
References
Learn about the terminology that Microsoft uses to describe software updates.