gistfile1.txt

  field_kilde_paragraphs:
    plugin: iterator
    source: kilde
    process:
      id:
        -
          plugin: migration
          source:
            - bibliotek_dk_url
            - linktekst
            - url
            - navn
            - tekst
            - linkgroupname
          migration: migrate_kilde_paragraphs
          no_stub: true
        -
          plugin: extract
          index:
            - id
Actual
$row->rawDestination['field_kilde_paragraphs'][
  0 => [
    'id' => [
      0 => 14795
      1 => 14796
    ],
  ],
  1 => [
    'id' => [
      0 => 14796
      1 => 14797
    ],
  ],
  2 => [
    'id' => [
      0 => 14797
      1 => 14798
    ],
  ],
];

Desired
$row->rawDestination['field_kilde_paragraphs'][
  0 => [
    'target_id' => 14795
    'target_revision_id' => 14796
  ],
  1 => [
    'target_id' => 14796
    'target_revision_id' => 14797
  ],
  2 => [
    'target_id' => 14797
    'target_revision_id' => 14798
  ],
];