Get tags and query posts by tags in Woocommerce

Hello,
I’ve been pulling my hair out for now 3 hours without finding any solution. I’m trying to query posts with same tag as my product tag.
I can echo my tag before my query (see first line of code), it works, but then inside the query it all goes wrong.

<?php echo $product->get_tags(); ?>
    <?php

     $producttags = get_tags();
if ($producttags) {
    foreach($producttags as $tag) {
        $tag = $tag->slug;  break;
    }
query_posts('tag='.$tag.'&posts_per_page=-1');
    while (have_posts()) : the_post(); ?>
    <div class="actucontent">
      <h3>
        <?php the_title(); ?>
      </h3>
      <?php the_content(); ?>
      <?php echo $tag ?> </div>
    <?php endwhile;
    wp_reset_query();
}

    ?>

BTW, webpage is https://www.tiwelle.com/sonneur/?product=lena
Any idea someone ?
Thank you,
Manue

https://www.ads-software.com/extend/plugins/woocommerce/