templates/emails/plain/failed-renewal-authentication.php

<?php
if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly
}

echo $email_heading . "\n\n";

// translators: 1) name of the blog, 2) link to checkout payment url, note: no full stop due to url at the end
printf( esc_html_x( 'The automatic payment to renew your subscription with %1$s has failed. To reactivate the subscription, please login and authorize the renewal from your account page: %2$s', 'In failed renewal authentication email', 'woocommerce-gateway-stripe' ), esc_html( get_bloginfo( 'name' ) ), esc_attr( $authorization_url ) );

echo "\n\n=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=\n";

do_action( 'woocommerce_subscriptions_email_order_details', $order, $sent_to_admin, $plain_text, $email );

echo "\n=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=\n\n";

echo apply_filters( 'woocommerce_email_footer_text', get_option( 'woocommerce_email_footer_text' ) );