Sindbad~EG File Manager

<?php
/**
 * Plugin Name: Disable Twenty Themes Installation
 * Description: Empêche WordPress d’installer automatiquement les thèmes "Twenty".
 */

add_filter('core_update_get_available_themes', function ($themes) {
    foreach ($themes as $slug => $theme) {
        if (strpos($slug, 'twenty') === 0) {
            unset($themes[$slug]);
        }
    }
    return $themes;
});