override cookie settings to comply with new browser reqs.

Model/Plugin/FixSession.php

@@ -0,0 +1,67 @@
+<?php
+
+/**
+ * Shop System Plugins - Terms of Use
+ *
+ * The plugins offered are provided free of charge by Qenta Payment CEE GmbH
+ * (abbreviated to Qenta CEE) and are explicitly not part of the Qenta CEE range of
+ * products and services.
+ *
+ * They have been tested and approved for full functionality in the standard configuration
+ * (status on delivery) of the corresponding shop system. They are under General Public
+ * License Version 2 (GPLv2) and can be used, developed and passed on to third parties under
+ * the same terms.
+ *
+ * However, Qenta CEE does not provide any guarantee or accept any liability for any errors
+ * occurring when used in an enhanced, customized shop system configuration.
+ *
+ * Operation in an enhanced, customized configuration is at your own risk and requires a
+ * comprehensive test phase by the user of the plugin.
+ *
+ * Customers use the plugins at their own risk. Qenta CEE does not guarantee their full
+ * functionality neither does Qenta CEE assume liability for any disadvantages related to
+ * the use of the plugins. Additionally, Qenta CEE does not guarantee the full functionality
+ * for customized shop systems or installed plugins of other vendors of plugins within the same
+ * shop system.
+ *
+ * Customers are responsible for testing the plugin's functionality before starting productive
+ * operation.
+ *
+ * By installing the plugin into the shop system the customer agrees to these terms of use.
+ * Please do not use the plugin if you do not agree to these terms of use!
+ */
+
+namespace Qenta\CheckoutSeamless\Model\Plugin;
+
+use Magento\Framework\HTTP\Header;
+use Magento\Framework\Stdlib\Cookie\PhpCookieManager;
+use Magento\Framework\Stdlib\Cookie\PublicCookieMetadata;
+
+
+class FixSession
+{
+    /**
+     * @var Header
+     */
+    protected $header;
+
+    public function __construct(Header $header)
+    {
+        $this->header = $header;
+    }
+
+    public function beforeSetPublicCookie(
+        PhpCookieManager $subject,
+        $name,
+        $value,
+        PublicCookieMetadata $metadata = null
+    ) {
+        if ($metadata && method_exists($metadata, 'getSameSite') && ($name == 'PHPSESSID')) {
+            if ($metadata->getSameSite() != 'None') {
+                $metadata->setSecure(true);
+                $metadata->setSameSite('None');
+            }
+        }
+        return [$name, $value, $metadata];
+    }
+}

etc/frontend/di.xml

@@ -50,4 +50,8 @@
             </argument>
         </arguments>
     </type>
+
+    <type name="Magento\Framework\Stdlib\Cookie\PhpCookieManager">
+        <plugin name="fixSession" type="Qenta\CheckoutSeamless\Model\Plugin\FixSession" />
+    </type>
 </config>