The module azure_rm_virtualmachine has fields for plan information. Module azure_rm_virtualmachinescaleset needs to have them and forward them when creating a VM with an image that requires plan info to be specified. The CIS hardened images from the Azure Marketplace is a prime example.

description:
            - Describes list of data disks.
        version_added: "2.4"
        suboptions:
            lun:
                description:
                    - The logical unit number for data disk.
                default: 0
                version_added: "2.4"
            disk_size_gb:
                description:
                    - The initial disk size in GB for blank data disks.
                version_added: "2.4"
            managed_disk_type:
                description:
                    - Managed data disk type.
                choices:
                    - Standard_LRS
                    - Premium_LRS
                version_added: "2.4"
            caching:
                description:
                    - Type of data disk caching.
                choices:
                    - ReadOnly
                    - ReadWrite
                default: ReadOnly
                version_added: "2.4"
    virtual_network_resource_group:
        description: