How to separate terms name with comma in an array?

I am trying to get taxonomies terms names separated with a comma. This is the code, but it separates taxonomies and terms with : If there are many terms they get separated with : instead of , If I delete the : symbol there are nothing in between taxonomy terms names.

<ul class='apt-product-terms'>
      <?php
        $_taxonomies = array(
            'taxname1'   =>   __( 'Taxname1', 'textstringdomain' ),
            'taxname2'   =>   __( 'Taxname2', 'textstringdomain' ),
            'taxname3'   =>   __( 'Taxname3', 'textstringdomain' ),
            'taxname4'   =>   __( 'Taxname4', 'textstringdomain' )
        );
 

        foreach ($_taxonomies as $taxonomy_slug => $taxonomy_name) {
          $terms = get_the_terms( $post->ID, $taxonomy_slug);
          if (is_array($terms) && count($terms) > 0) {
      ?>

      <li class='apt-tax-item'>
        <span class='apt-term-name'><?php echo $taxonomy_name  ?></span>
        <ul class='apt-tax-term-list'>
        <?php
          foreach ( $terms as $term ) {

          ?>
            <li class='apt-term-item'>: 
              <a class='apt-term-link' href="<?php echo get_term_link($term); ?>"> <?php echo $term->name ?></a>           
            </li>
          <?php
          } 
        ?>
        </ul>
      </li>

      <?php            
        }
          }  
      ?>
    </ul>

Where is the problem. I think it might be related to echo $term->name

source https://stackoverflow.com/questions/71651140/how-to-separate-terms-name-with-comma-in-an-array