Powering off ESX agent VM cause all the regular VMs to migrate out of the host in a DRS enabled cluster.
In the vpxd logs, you will see vmotion related errors for other vms in the cluster
2023-01-04T07:12:11.962Z info vpxd[06256] [Originator@6876 sub=cdrsPlmt opID=CdrsLoadBalancer-60b7acd9] Vm [vim.VirtualMachine:vm-8029,Panorama-ESX] failed constraint check false on host [vim.HostSystem:host-28,esx03.lab.local] with <obj xmlns:xsd=http://www.w3.org/2001/XMLSchema xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance xmlns="urn:vim25" versionId="7.0.3.0" xsi:type="LocalizedMethodFault"><fault xsi:type="InsufficientAgentVmsDeployed"><hostName>esx03.lab.local</hostName><requiredNumAgentVms>1</requiredNumAgentVms><currentNumAgentVms>0</currentNumAgentVms></fault><localizedMessage></localizedMessage></obj>
This issue occurs when required number of esx agent vms powered on a host within a DRS enabled cluster is less than the actual number of powered on esx agent vms on the host.
DRS cluster advance option "numAgentVmsRequired" indicates the required number of esx agent vms powered on a host within a DRS enabled cluster and option is set by EAM service. When set, DRS will ensure that all hosts has the required number of esx agent vm powered on and if not DRS load balancer will gradually migrate the regular vms from this host to other hosts in cluster which has the required number of esx agent vm and also DRS will not allow poweron or migration of regular vm into the host that does not have the required number of esx agent vms.
Note - Manually Changing this advanced option numAgentVmsRequired has no effect. Since this option is controlled by EAM service.
ESX agent VM deployed on the host within a DRS enabled cluster should not be powered off by a user.