KB4167: NFS share cannot be used - Veeam Software
https://www.veeam.com/kb416719.05.2021 · When the next Guest Files restore begins the Veeam software detects that the NFS Datastore needs to be remounted and attempts to send requests for a new datastore to be created. This operation fails because the ESXi host kept the share name in the cache and does not allow the mounting of a share with the same name.