Selectively Deactivating Lazy Load In Wordpress

function modify_post_thumbnail_html($html, $post_id, $post_thumbnail_id, $size, $attr) {
    $id = get_post_thumbnail_id();
    $src = wp_get_attachment_image_src($id, $size);
    $alt = get_the_title($id);
    $class = $attr['class'];
    if (strpos($class, 'retina') !== false) {
        $html = '<img src="' . $src[0] . '" alt="' . $alt . '" class="' . $class . '" />';
    } else {
        $html = '<img src="' . $src[0] . '" alt="' . $alt . '" class="' . $class . '" />';
    }
    return $html;
}
add_filter('post_thumbnail_html', 'modify_post_thumbnail_html', 99, 5);