Hi Leandro Castor,
Thanks for reaching out to Microsoft Q&A.
For Azure Backup for SQL Server on VMs, there are no charges for the data traffic when backing up to a Recovery Services Vault. Azure does not charge for the ingress traffic (data sent to the vault). However, there are other associated costs with Azure Backup that you should be aware of:
Backup Storage Costs: The amount of data stored in the Recovery Services Vault incurs charges. You can choose between LRS (Locally Redundant Storage) or GRS (Geo-Redundant Storage) based on your redundancy needs, and the cost will depend on the storage option and the amount of data backed up.
Backup Instance Charges: Azure Backup charges are based on the size of the SQL Server databases being protected. There are different pricing tiers depending on the size of the protected instance (e.g., small, medium, large).
While the data transfer to the vault (ingress) is free, you should account for the storage and instance charges as part of your overall backup cost.
Please 'Upvote'(Thumbs-up) and 'Accept' as an answer if the reply was helpful. This will benefit other community members who face the same issue.