A cluster becomes overcommitted (yellow) when the tree of resource pools and virtual machines is internally consistent but the cluster does not have the capacity to support all the resources reserved by the child resource pools. See also: https://docs.vmware.com/en/VMware-vSphere/8.0/vsphere-resource-management/GUID-ED8240A0-FB54-4A31-BD3D-F23FE740F10C.html