Bulk custom pdf generation prints same content

I have a node that has paragraphs that hold information about event details. Node has general information, and paragraphs have listed attendees (name, surname, other personal data). Bases on that I want to generate certificates.

I have a custom function that generates certificates from paragraphs when I hit a button, like this (with reduced custom code):

function _generate_certificates(&$form, $form_state) {
  $entity = $form_state->getFormObject()->getEntity();
  $paragraphs = $entity->field_attendee_list_para->referencedEntities();

  foreach ($paragraphs as $paragraph) {
    $pid = $paragraph->id();
    $filename =  $pid . '.pdf';

    /** @var Drupal\entity_print\Plugin\EntityPrintPluginManager $print_engine_service */
    $print_engine_service = Drupal::service('plugin.manager.entity_print.print_engine');
    $print_engine = $print_engine_service->createSelectedInstance('pdf');

    /** @var Drupal\entity_print\PrintBuilderInterface $print_service */
    $print_service = Drupal::service('entity_print.print_builder');
    $generated_file = $print_service->savePrintable([$paragraph], $print_engine, 'private', $filename, FALSE);
    // custom stuff
  }
}

Not sure if that's intended, but if $print_engine is outside of foreach() loop, paragraph variables printed out in pdf are the same for all generated files with 1st paragraph values (so all certificated looks the same). Once I set $print_engine in each loop, the printed content is correct (as in code above).
My first thought was that when passing [$paragraph] to savePrintable(), it would be enough information to give. Should I really set $print_engine_service->createSelectedInstance('pdf') for each paragraph? Is that intended? I think by passing correct entity, it should give correct output in file. When debugging where root cause is, found that HTML passed back by generateHtml() HTML is correct each time. So $print_engine is cruel part. I guess..

Not sure if this is a bug or a feature and as I solved this by moving lines a bit, I didn't dig deeper. Hope someone will check this more closely.
And maybe someone finds this helpful as I struggled with this for half a day. :)

Using: wkhtmltopdf
entity_print: 2.14
Drupal: 10.2.4