Display users webform submission as readonly?
I have done an identical task, unfortunately this one of those unique use cases. Here is a snipped in my hook_form_alter

Basically, assuming there is no page element (not multi page):

if ($cutoff_time &gt; $current_time) {

  $form['elements']['field_name']['#disabled'] = TRUE;

  $messenger = \Drupal::messenger();
  $messenger-&gt;addMessage(t('Time has expired, you can no longer change the value'), $messenger::TYPE_WARNING);

}


Otherwise (multipage):

$form['elements']['page_name']['field_name']['#disabled'] = TRUE;