virtctl vmexport download vm1-export --vm=rhel9-scarlet-cricket-55 --manifest --include-secret --output=manifest.yaml

VM manifest dataVolumeTemplates - has both "source" and "sourceRef", which results in a cloning from a DataSource 
VM manifest dataVolumeTemplates - should only have a "source"

4.16, 4.15, probably in earlier versions as well

Always

1. Create a VM from a DataSource (in UI, for example)

2. Run 
virtctl vmexport download vm1-export --vm=rhel9-scarlet-cricket-55 --manifest --include-secret --output=manifest.yaml

3. See the VM manifest:

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  annotations:
    kubemacpool.io/transaction-timestamp: "2024-04-10T11:48:03.276130493Z"
    kubevirt.io/latest-observed-api-version: v1
    kubevirt.io/storage-observed-api-version: v1
    vm.kubevirt.io/validations: |
      [
        {
          "name": "minimal-required-memory",
          "path": "jsonpath::.spec.domain.memory.guest",
          "rule": "integer",
          "message": "This VM requires more memory.",
          "min": 1610612736
        }
      ]
  creationTimestamp: null
  labels:
    app: rhel9-scarlet-cricket-55
    kubevirt.io/dynamic-credentials-support: "true"
    vm.kubevirt.io/template: rhel9-server-small
    vm.kubevirt.io/template.namespace: openshift
    vm.kubevirt.io/template.revision: "1"
    vm.kubevirt.io/template.version: v0.27.0
  name: rhel9-scarlet-cricket-55
  namespace: default
spec:
  dataVolumeTemplates:
  - apiVersion: cdi.kubevirt.io/v1beta1
    kind: DataVolume
    metadata:
      creationTimestamp: null
      name: rhel9-scarlet-cricket-55
    spec:
      source:
        http:
          certConfigMap: export-ca-cm-vm1-export
          secretExtraHeaders:
          - header-secret-vm1-export
          url: https://virt-exportproxy-openshift-cnv.apps.<SERVER>/api/export.kubevirt.io/v1alpha1/namespaces/default/virtualmachineexports/vm1-export/volumes/rhel9-scarlet-cricket-55/disk.img.gz
      sourceRef:
        kind: DataSource
        name: rhel9
        namespace: openshift-virtualization-os-images
      storage:
        resources:
          requests:
            storage: 30Gi
  running: false
  template:
    metadata:
      annotations:
        vm.kubevirt.io/flavor: small
        vm.kubevirt.io/os: rhel9
        vm.kubevirt.io/workload: server
      creationTimestamp: null
      labels:
        app.kubernetes.io/name: headless
        kubevirt.io/domain: rhel9-scarlet-cricket-55
        kubevirt.io/size: small
    spec:
      architecture: amd64
      domain:
        cpu:
          cores: 1
          sockets: 1
          threads: 1
        devices:
          disks:
          - disk:
              bus: virtio
            name: rootdisk
          - disk:
              bus: virtio
            name: cloudinitdisk
          interfaces:
          - macAddress: "02:04:17:00:00:09"
            masquerade: {}
            model: virtio
            name: default
          networkInterfaceMultiqueue: true
          rng: {}
        features:
          acpi: {}
          smm:
            enabled: true
        firmware:
          bootloader:
            efi: {}
        machine:
          type: pc-q35-rhel9.4.0
        memory:
          guest: 2Gi
        resources: {}
      networks:
      - name: default
        pod: {}
      terminationGracePeriodSeconds: 180
      volumes:
      - dataVolume:
          name: rhel9-scarlet-cricket-55
        name: rootdisk
      - cloudInitNoCloud:
          userData: |-
            #cloud-config
            user: cloud-user
            password: egau-yftp-m1y2
            chpasswd: { expire: False }
        name: cloudinitdisk
status: {}

Both "source" and "sourceRef" are in the dataVolumeTemplates, which results in cloning from a DataSource, but not exporting the source PVC

Only "source" in the dataVolumeTemplates