Okay, I’ve asked my host to tell me (if this happens again) what was the responsible query.
About the LIKE in the SQL, here was a solution : double the %
$loc = '"what im looking for"';
$posts_query = $wpdb->get_results("...... NOT LIKE '%%$loc%%' ....);
Again, many thanks !! It works perfectly (see here it’s a temporal link while the site is under construction) 🙂