This topic is relevant if you are using vSphere 6.7 and later, on non-vSAN datastores. In vSphere version 6.7 and later, VMFS-6 supports the Automatic UNMAP feature, which reclaims dead blocks automatically and asynchronously (if it is not disabled by the vSphere or vCenter Server administrator). Therefore, the periodic space reclaim operations by Horizon do not reclaim significant space.
In Horizon Console, the option Space reclaimed in the latest run over the last 7 days typically shows a value of 0.00 GB, since this is an indication of the specific Horizon periodic space reclamation operations.
Unless you have disabled automatic UNMAP feature on vSphere or vCenter, no action is needed on Horizon to reclaim space.