ajax not working since a I updated the .htaccess - php

Question

as I recently updated several htaccess in my wordpress site, I observed that the php/ajax code is no more working. I do not understand why
here is my button
$generer_liste_all_plongeurs ='<table><tr>
<td><form>
<button type="submit" id="btn-submit_all">Générer une liste de TOUS les plongeurs</button>
<input type="hidden" id="eventid_all" value="NO_ID" />
<input type="hidden" id="eventdate_all" value="NO_DATE" />
</form></td>
<td><div id="response">
<!-- Nous allons afficher un retour en jQuery au visiteur -->';
/* si le fichier existe, on va l'afficher */
//https://asmtplongee.org/wp-content/FdP/Tous_les_plongeurs.csv
$fichier="Tous_les_plongeurs.csv";
if (file_exists($dir . "/" . $fichier)) {
$generer_liste_all_plongeurs .= '' . 'Liste de plongeurs générée le ' . date ("F d Y H:i:s", filemtime($dir . "/" . $fichier)) . "";
}
$generer_liste_all_plongeurs.= '
</div></td></tr></table>';
and the code to treat this
//script pour ajax
$o .='<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script>$(document).ready(function(){
$("#btn-submit_all").click(function(e){
e.preventDefault();
$.post(
"' . get_site_url() . '/wp-content/plugins/alex/creation_csv_palanq.php",
{
eventid : "NO_ID",
eventdate : "NO_DATE",
},
function(data){
$("#response").html("<p>" + data + "</p>");
},
"text"
);
});
});
</script>';
//fin du chapitre ajax
I want the page creation_csv_palanq.php to be called with the below args and their values
eventid : "NO_ID",
eventdate : "NO_DATE",
the content of the htaccess located in wp-content is:
# Alternative to prevent directory listing
IndexIgnore *
# Hide the information from server
ServerSignature Off
# Bloque les accès directs aux fichiers PHP (Merci à Sucuri)
<FilesMatch "\.(?i:php)$">
<IfModule !mod_authz_core.c>
Order allow,deny
Deny from all
</IfModule>
<IfModule mod_authz_core.c>
Require all denied
</IfModule>
</FilesMatch>