During the greenfield deployment of VMware Cloud Foundation (VCF) 9.1 or vSphere Foundation (VVF) 9.1 using the VCF Installer, virtual machine (VM) names are generated with random characters appended to the end of the Fully Qualified Domain Names (FQDNs), even when the names were pre-filled in the deployment wizard.
This is by design. The hostname from the FQDN for runtime services is prefixed to the names of its node VMs and related objects.
Runtime services requires multiple VMs and thus each VM has its own unique name tied to either a control plane or worker node.
This would also apply for any clustered VMs that are deployed within VCF, such as vSphere Operations, VCF Automation, etc.
See also: Start a New vSphere Foundation Deployment by Using the VCF Installer Deployment Wizard