we have multiple 10TB+ Fileservers (even with Windows Dedupe enabled so actual data is about 3-5x that much). Due tue Dedupe changerate is quite high but still we have no issues at all backing them up with veeam since i can remember.
Restoring the VM in an emergency is certainly not the easiest (quickest), but that is what replica's are for
If your underlying Storage / Repository is performant there should be no issues, but since it seems like you are doing some kind of agent backup and that's working Veeam should be your littlest problem. Have all components up to date always makes a big difference. ReFS and upcoming vmfs-6 when veeam support is released should be a great combination