Using JSON:API to replicate content on external location
For consideration, an interesting way do this that was suggested to me by gabesullice, is to deny access to the fields. This also resulted a performance improvement in jsonapi 1.x, maybe 2.x as well.

/**
 * Implements hook_entity_field_access().
 */
function MYMODULE_entity_field_access($operation, $field_definition, $account, $items = NULL) {

  $request = \Drupal::request();
  if (strstr($request-&gt;getUri(), '/jsonapi/node/')) {
    $name = $field_definition-&gt;getName();
    switch ($name) {
      case 'field_blah':
      case 'uid':
      case 'moderation_state':
      case 'promote':
      case 'sticky':
      case 'unpublish':
      case 'review_date':
      case 'vid':
      case 'type':
      case 'revision_translation_affected':
      case 'revision_timestamp':
      case 'revision_log':
      case 'revision_id':
      case 'revision_uid':
      case 'langcode':
      case 'default_langcode':
        return AccessResult::forbidden();
    }
  }
  return AccessResult::neutral();
}