Hi @alihs
I hope the code you showed is an excerpt and you still have
$date_now = current_time('timestamp');
somewhere and also your $date_listing value is a Unix timestamp (integer).
For the second case: this AJAX action is used by the WP admin to refresh some index statistics, it does not have any parameters (that's why "z" is empty here).
The message you see means that 257 posts were processed by an outdated version of one or more indexing rules and WPFTS wants to reindex them to bring everything into compliance.
You can open the page with the list of rules and see which indexing rules are not compliant.
You can also send me a screenshot so I can help you figure this out.
By the way, this may be due to the fact that you somehow change some posts from the code, but do not call the "save_post" hook, which triggers reindexing under the hood. Because of this WPFTS considers these posts outdated. If the number of posts controlled by the rule is not 257, then this is exactly the case.
Let me know if you have more information.
Thanks!