Implement end-to-end encryption for the backup data only during transit to the cloud, assuming the cloud provider ensures encryption at rest.

Define and enforce comprehensive security requirements for the backup solution, including role-based access control (RBAC), data encryption in transit and at rest, data retention policies aligned with compliance standards, and schedule regular third-party security assessments.

Focus solely on securing the network infrastructure and endpoints accessing the backup solution, leveraging Azure Firewall and Network Security Groups (NSGs) to restrict access.

Depend entirely on the cloud provider's built-in security features for backup data, assuming they meet all compliance and security requirements without additional configuration.