'get_extended' breaks when using 'more' gutenberg block

[joewebber]

'get_extended' returns the closing tag <!-- /wp:more -->' in the extended content, which prevents 'the_content' filter from working correctly.

Steps to replicate:

<?php
// Fetch post content
$content = get_post_field('post_content', get_the_ID());

// Get content parts
$content_parts = get_extended($content);

echo apply_filters('the_content', $content_parts['extended']);

Quick workaround (wp-includes/post.php line: 592):

<?php
$post = str_replace('<!-- /wp:more -->', '<!-- /more -->', $post);

[pento]

Related: #46471.