Symptoms:
The Controller firmware is VMware certified health check might report a false warning when multiple supported firmware versions are available for a particular controller.

The vSAN HCL database currently allows only one supported firmware version for each controller type. The controller firmware check might report a warning if the current firmware version does not match the HCL database, even if the firmware is listed in the VMware Compatibility Guide.

VMware vSAN 6.6.x

This issue is resolved in VMware vSAN 6.5U2 and later versions, available at VMware Downloads.