For example, after updating vCenter Server from version VCF 9.0.2 to to VCF 9.1.0, the vCenter Server Extension "vService Manager" remains on the previous version while other plug-ins/extensions may be updated to the the same version value as vCenter Server:
VMware vCenter Server 8.0.x
VMware vCenter Server 9.x
It is a purely cosmetic issue for "built-in" extensions. VSM is a built-in extension, and its version number does not serve any external purposes.
This issue is not an operational problem, and the service will be updated when transitioning to a later version.