WordPress Version: 6.1
/**
* Adds a nonce field to the signup page.
*
* @since MU (3.0.0)
*/
function signup_nonce_fields()
{
$id = mt_rand();
echo "<input type='hidden' name='signup_form_id' value='{$id}' />";
wp_nonce_field('signup_form_' . $id, '_signup_form', false);
}