The parameter "Managed by" is managed by vCenter Extension (third party VC Extension in this case). HCX does not have integration to third party VC extensions, therefore, this parameter is not migrated by HCX.
Data Object - VirtualMachineConfigSpec(vim.vm.ConfigSpec)
| managedBy* | ManagedByInfo |
Specifies that this VM is managed by a VC Extension. This information is primarily used in the Client to show a custom icon for managed virtual machines, and a description of the function of the virtual machine. If no extension can be found with the extension key in the managedBy object, or the type is not found in the managedEntityInfo list of the extension, the default virtual machine icon is used, and no description is shown. To unset this field pass a ManagedByInfo object with an empty extensionKey. Reconfigure privilege: VirtualMachine.Config.ManagedBy |