Azure Backup now supports BEK-encrypted Azure virtual machines
Azure Backup supports backup and restore of Azure virtual machines that have managed or unmanaged disks encrypted through BitLocker Encryption Key (BEK) or through a combination of BEK and Key Encryption Key (KEK).
This support is available when you're using the Azure portal and PowerShell. Azure Backup supports all these scenarios seamlessly and maintains the security of enterprise data throughout the backup lifecycle.
For more info, read the official blog.