It looks like the option to select "BlobStorage" is missing from the backup configuration interface. This might be due to a few reasons:
Ensure that the feature for backing up Azure Blobs is available in your region and subscription. Azure periodically updates its services, and some features might be in preview or not yet available in all regions. Verify that you have the necessary permissions to configure backups for the storage account. You need to have at least the "Contributor" role on both the Recovery Services vault and the storage account.
Confirm that your storage account is of the type "BlockBlobStorage." Some storage account types might not be supported for this backup feature.
Service Registration: Ensure that the Microsoft.DataProtection resource provider is registered for your subscription. You can do this by navigating to your subscription in the Azure portal, selecting "Resource providers," and registering the Microsoft.DataProtection provider if it is not already registered.
If you have any other questions or are still running into more issues, let me know in the "comments" and I would be happy to help you.