Transient Code affecting comments

I am using this code in single posts but it is affecting my comments (changing the comments of the post to the last post appearing in the sequence). Could someone guide me on how to stop this from happening?

<?php
// Get any existing copy of our transient data
if ( false === ( $special_query_results = get_transient( 'special_query_results' ) ) ) {
    // It wasn't there, so regenerate the data and save the transient
    $randargs = array('orderby' => 'rand', 'numberposts' => 20);
    $special_query_results = get_posts($randargs);
    set_transient( 'special_query_results', $special_query_results, 60*60*12 );
}
 
// Use the data like you would have normally...
$randomposts = get_transient( 'special_query_results' );
$randkey = array_rand( $randomposts, 6 );
$sixposts[0] = $randomposts[$randkey[0]];
$sixposts[1] = $randomposts[$randkey[1]];
$sixposts[2] = $randomposts[$randkey[2]];
$sixposts[3] = $randomposts[$randkey[3]];
$sixposts[4] = $randomposts[$randkey[4]];
$sixposts[5] = $randomposts[$randkey[5]];
 
global $post;
foreach( $sixposts as $post ) :  setup_postdata($post); ?>
 
<div class="gridcontainer">
<div class="gridthumb"><a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_post_thumbnail(); ?></a></div>
<div class="gridcontent">
<div class="gridtext"><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></div>
</div>
</div>
 
<?php endforeach; ?>

Source of code: https://www.wpbeginner.com/wp-tutorials/speed-up-your-wordpress-by-caching-custom-queries-using-transients-api/