It looks like you have more than one feed. Go to this page and enter the intended feed ID in your shortcode like this:

Ce message est uniquement visible par les administrateurs/administratrices.
Problème d’affichage des publications Facebook. Mise en cache de sauvegarde en cours.
Cliquer pour afficher l’erreur
Erreur: Error validating access token: The session has been invalidated because the user changed their password or Facebook has changed the session for security reasons. Type: OAuthException
.

It looks like you have more than one feed. Go to this page and enter the intended feed ID in your shortcode like this:

Ce message est uniquement visible par les administrateurs/administratrices.
Problème d’affichage des publications Facebook. Mise en cache de sauvegarde en cours.
Cliquer pour afficher l’erreur
Erreur: Error validating access token: The session has been invalidated because the user changed their password or Facebook has changed the session for security reasons. Type: OAuthException
.