In case this is the original sourcecode, there are two asterix pairs, which might break your code (getting interpreted as comments and therefore are not visible).
Remove these and it should work.
<?php
// Start the loop
if(have_posts() ) : ?>
<?php while (have_posts()) : the_post(); ?>
<?php $format = get_post_format(); ?>
<article id="post-<?php the_ID(); ?>" <?php post_class($format); ?>>
<?php the_title(); ?>
<?php the_category(); ?>
<?php the_date(); ?>
<?php the_excerpt(); ?>
<?php the_tags('<ul class="taglist"><li>', '</li><li>', '</li></ul>'); ?>
<a href="https://wordpress.stackexchange.com/questions/360729/<?php the_permalink(); ?>">read more</a>
</article>
<?php endwhile; ?>