How to update custom fields via update_field?

Question

WordPress

There is a code with which I select all posts and update the service field in them. But the problem is that a post, for example, has 5 services, but the first service is taken and duplicated. Tell me what am I doing wrong?

$recent2 = new WP_Query(
    array(
      'orderby' => '',
      'showposts'=>-1,
       )
  );
      while($recent2->have_posts()) : $recent2->the_post() ;
        $count = get_field('uslugi');
        update_field('uslugi', $count);
      ?>
  <?php endwhile; ?>
  <?php wp_reset_query() ; ?>

When updating an additional field in which there is only 1 value, everything is ok. If there are several values ​​(for example, a custom field of the taxonomy type), then the first value is taken and duplicated.