doitinpoland.com/wp-content/plugins/sitepress-multilingual-cms/res/js/wpml-language-per-domain-sso.js

jQuery(function ($) {
    'use strict';

    $('.wpml_iframe').on('load', function () {
        var userStatus = 'wpml_is_user_signed_out';

        if (wpml_sso.is_user_logged_in) {
            userStatus = 'wpml_is_user_signed_in';
        }

        this.contentWindow.postMessage(JSON.stringify({userStatus: userStatus, userId: wpml_sso.current_user_id}), "*");
	});
});