Can’t echo all coauthors in loop

Hello,

I did a summary of different pages with a while loop and call children of pages when they have some with a foreach, and I call the coauthors for each of them as I did in the single pages, but when there is more than one author, I just can see the first of them :

<ul id="home-slider-nav">

      <?php $my_query = new WP_Query($args);
            if ($my_query->have_posts()) {
               while ($my_query->have_posts()) : $my_query->the_post();
                 $posts = get_field('connexe_article_new');
      ?>

         <li class="separator-h">
            
            <h5 class="separator-h"><?php if(!$posts): ?><a href="<?php the_permalink() ?>"><?php the_title() ?></a><?php else: ?><?php the_title() ?><?php endif ?></h5>

            <?php if($posts):
                  $total = count($posts); ?>
            <ol>
               <?php foreach($posts as $key=>$post):
                     setup_postdata($post); 
               ?>
               <li<?php if(($key+1)!=$total){ echo ' class="separator-h"';}elseif(($key+1)==$total){ echo ' style="padding:0"';} ?>>
                  <h6 class="no-c"><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h6>
                  <p class="cat">par <?php echo coauthors(', ',', ', null,null,false); ?></p>
               </li>

               <?php endforeach; ?>
            </ol>

         <?php else: ?>
            <div>
            <?php echo'<p class="separator-h no-c cat"> par <span>'.coauthors(', ',', ', null,null,false).'</span></p>'; ?>
               <p class="cat"><b><?php echo get_first_category(); ?></b><span class="excerpt separator-l"><?php echo get_the_excerpt(); ?></span></p>
            </div>

         <?php wp_reset_postdata();
               endif;
         ?>
      </li>

      <?php endwhile;
            wp_reset_postdata();  // Restore global post data stomped by the_post().
         } // if ($my_query)
      ?>
      </ul>

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