问Wordpress:循环中的preg_replace只偶尔工作

EN

<?php while (have_posts()) : the_post(); ?>
  <?php echo processPostContent(); ?>
<?php endwhile; ?>

function processPostContent() {
    $post = get_post(get_the_ID());
    $post_content = strval($post->post_content);
    // replace h3 and h4 tags with h2
    $post_content = preg_replace('/<(\/?)h((?![12])\d)/im', "<$1h2", $post_content);
    // strip every attribute of <img> other than src
    $post_content = preg_replace('/<img[^>]*(src="[^"]*")[^>]*>/im', "<img $1 />", $post_content);
    // insert text after some closing tags
    $post_content = preg_replace('/<\/(h2|p|figure)>/im', "</$1><p>Inserted</p>", $post_content);

    return $post_content;
}