Query block in front end renders only the first element

[ntsekouras]

Describe the bug
Something recently broke the rendering of Query block in front-end. While the query block works as expected in FSE, when trying to view the page in front-end, only the first element is displayed.

In some searching I've done, I noticed in query-loop/edit.js:

1. That $posts = get_posts( $query ) are correct
2. The $content is not because it's missing the post-contents but do have all post-titiles. It still renders only the first one though.

Also by changing the query-loop/save.js to return a div wrapper to apply the block's attributes ( which in this case is class=wp-block-query-loop), the rendered output in front-end is both post-title and post-content but only for the first item..

I have searched many recent PRs but I haven't found the cause of this and WP_Block class hasn't changed for a couple of months (https://github.com/WordPress/gutenberg/blob/master/lib/class-wp-block.php).

To reproduce
Steps to reproduce the behavior:

1. Enable FSE and add a Query block
2. Observe that in editor everything works as expected
3. View the page in front-end
4. Observe the missing rendered things/parts

Expected behavior
Rendered parts/posts should be the same as in the editor