vCenter 9.1 introduces the Quick Patch feature to update systems without interrupting workload management. However, early patch releases do not support this functionality. Attempting to use Quick Patch on unsupported builds will not show as available.
VMware vCenter 9.1.0.x
VCF 9.1 patches do not universally support Quick Patch functionality.
Quick Patch availability depends strictly on the services updated in each package.
Apply the patch using standard update procedures.
The vCenter 9.1.0.0300 Release Notes explicitly list Quick Patch support as No.
Release notes for versions 9.1.0.0100 and 9.1.0.0200 omit this entry. However, these versions are also unsupported for Quick Patch.