Steps to reproduce:

1. You need a VM on VMware vSphere Hypervisor with Windows (e.g. 10.0.17763 Microsoft Windows Server 2019 Standard x64 )
2. Check CPU NUM:

   zabbix_get -s 10.10.10.10 -k system.cpu.num
   20
   

3. Check CPU Discovery:

   zabbix_get -s 10.10.10.10 -k system.cpu.discovery
   [{"{#CPU.NUMBER}":0,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":1,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":2,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":3,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":4,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":5,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":6,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":7,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":8,"{#CPU.STATUS}":"online"},{"{#CPU.NUMBER}":9,"{#CPU.STATUS}":"online"}]
   

zabbix_get -s 10.10.10.10 -k agent.version
6.0.17

Result:
Only 9 CPUs are returned