bug of _csrf_token requied in Symfony

Some times, when you work with symfony forms in this way:

<form action="<?php echo url_for('@sf_guard_signin') ?>" method="post">
        
        <?php echo $form['username']->renderLabel(); ?>
        <?php echo $form['username']; ?>
        
        <?php echo $form['password']->renderLabel(); ?>
        <?php echo $form['password']; ?>

        <label class="checkput">
            <?php echo $form['remember']?>
            <?php echo $form['remember']->renderLabel(); ?>
        </label>
          
          <input type="submit" value="<?php echo __('Envoyer', null, 'sf_guard') ?>" />
    </form>

It will return _csrf_token is requied.

Now what you need to do is just add:

<?php echo $form['_csrf_token']; ?>