Ниже изменения работают на меня.
.htaccess
SetEnvIf Origin "^http(s)?://(.+\.)?(www\.example.com|www\.different.com)$" origin_is=$0
Header always set Access-Control-Allow-Origin %{origin_is}e env=origin_is
Страница благодарности
https://different.com
amp_thankyou. php
header("Content-type: application/json");
header("Access-Control-Allow-Credentials: true");
$valid_cors = array("www.example.com","www.different.com");
if(in_array($_SERVER['HTTP_ORIGIN'],"https://".$valid_cors)) {
header('Access-Control-Allow-Origin: https://{$valid_cors}', false);
header("Access-Control-Allow-Methods: GET, POST, PUT");
header("Access-Control-Allow-Headers: Content-Type");
}
header('AMP-Access-Control-Allow-Source-Origin: '.'http://'. $_SERVER['HTTP_HOST']);
header("AMP-Redirect-To: https://www.different.com/amp_thankyou.php");
header("Access-Control-Expose-Headers: AMP-Access-Control-Allow-Source-Origin, AMP-Redirect-To");