I got a esxi host thats has 256gb memory and host utilization is only at 71% showin in vcenter
but esxtop is showing swapping and memory compression already.
In certain scenarios, host memory reclamation happens regardless of the current host free memory state. For example, even if host free memory is in the high state, memory reclamation is still mandatory when a virtual machine’s memory usage exceeds its specified memory limit. If this happens, the hypervisor will employ ballooning and, if necessary, swapping and memory compression to reclaim memory from the virtual machine until the virtual machine’s host memory usage falls back to its specified limit.
This might help you know what may be problem: