There are no filters in get_the_category_list
function, that will allow you to add title attribute to those links, so you’ll have to write your own code for that…
<?php
$categories = get_the_category();
foreach ( $categories as $i => $cat ) :
if ( $i ) echo ', ';
?>
<a href="https://wordpress.stackexchange.com/questions/320140/<?php echo esc_url( get_category_link( $category->term_id ) ); ?>" ><?php echo $category->name; ?></a>
<?php endforeach; ?>