Azure Backup Job size

I would like to be able to get the size of Azure Backups. Preferably in both a Recovery Services vault and a Backup vault. I am using the Go SDK. For Backup Vaults I am using https://pkg.go.dev/github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/dataprotection/armdataprotection/v3#JobsClient.NewListPager function which supposedly returns a AzureBackupJobResource.Properties.ExtenedInfo.DataTransferredInBytes field which might be helpful, however it is always nil. And for Recovery Services all I can find is Vault Usage https://video2.skills-academy.com/en-us/rest/api/recoveryservices/usages/list-by-vaults?view=rest-recoveryservices-2024-04-01&tabs=Go but that seems to only give info at the vault level not the jobs level. Is any way to get this info? Thanks