Virtual machines previously deployed on a resource pool are deployed to a different location, such as a cluster.
vCenter Server 7.x, vCenter Server 8.x
When an ESXi host is re-registered with vCenter Server, virtual machines on ESXi are not deployed to their original resource pool.
After re-registering the ESXi host, you need to deploy the virtual machines to the desired resource pool again.
Japanese KB: 仮想マシンの配置先がリソースプールから変更されている