In vSphere 7 Update 1, vSphere Clustering Service (vCLS) was introduced, it basically provides DRS and HA even if vCenter server is down, cool 
Read all about it here: vSphere 7 Update 1 – vSphere Clustering Service (vCLS) – VMware vSphere Blog
When backup up with Veeam Backup and Replication 10a, you will get failures, because of missing Linux credentials, you could disable Application aware backup, but as the vCLS VM’s are maintainted completely by the ESX agent, there are NO need to backup theese VM’s, as they are deleted/created when the server wants them to and they are only for running the environment as a “helper” VM.
Until then, make an exception in Veeam for the vCLS VM’s
