Unexpected behavior in post loop after sending AJAX request

Hello everyone, I just updated to WordPress 6.3 version, and I have a weird behavior which I can’t figure out how to solve.

I run a custom WP Query where I fetch posts, and I use the excerpt_length and excerpt_more filters to filter the excerpt of the posts. This works fine when the loop runs on the page initially, but when I’m using the exact same query from the AJAX callback it doesn’t apply that filter at all.
This was working fine prior to upgrading to WP 6.3 so I’m not sure what changed now..
This is the query args I use, it’s a simple wp query

$args = array(
 'post_type' => 'post',
 'posts_per_page' => 12,
 'post_status' => 'publish',
 'fields' => 'ids',
);