Because Veeam can be good, but it's only as good as the user pays for. I do ransomware recovery and incident response management for a living. More often than not, Veeam is implemented poorly and does not do what the customer thinks they paid for.
It's not specifically fault of the product. However, in my experience in this field, the only time client backups are encrypted is due to a false sense of security due to negligence and ignorance.
Veeam should not be configured by an inexperienced or underfunded tech staff.