newsupernova/vendor/magento/module-customer/view/frontend/templates/additionalinfocustomer.phtml

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

// @codingStandardsIgnoreFile

?>
<?php
/**
 * Customer additional info for register and login forms
 *
 */
?>
<?php if ($this->helper('Magento\Checkout\Helper\Data')->isContextCheckout()): ?>
    <input name="context" type="hidden" value="checkout" />
<?php endif; ?>