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Problem:
When my magento2.3 application redirects user to payment gateway, i can access all the session data. but when it returns backs from there it do not have checkout session data or any session data. this happens only for google chrome

Things i already explored
From google chrome release notes (https://www.chromium.org/updates/same-site) i can see they have changed samesite default value to "Lax", and disabling this works.

Solution Looking for
I want to give samesite=None value to all my outgoing requests to any third party services. Any help or lead would be highly appreciated.

Answers

You can try setting the samesite=None by following steps..

file : etc/frontend/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Framework\View\Element\Js\Cookie">
        <plugin name="afterGetPath" type="namespace\module\Plugin\View\Element\Js\ManagePath" sortOrder="10"/>
    </type>
</config>

file : Plugin/View/Element/Js/ManagePath.php

namespace namespace\module\Plugin\View\Element\Js;

use Magento\Framework\View\Element\Js\Cookie;

class ManagePath
{
    public function afterGetPath(\Magento\Framework\View\Element\Js\Cookie $subject, $path)
    {
        
        if (preg_match('/SameSite/', $path)) {
             $path_array = explode(';', $path);
             $path = $path_array[0];
        }
        
        return $path;
    }
}

file : etc/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <preference for="Magento\Framework\Session\Config\ConfigInterface" type="namespace\module\Session\CustomConfig"/>
</config>

file : Session/CustomConfig.php

namespace namespace\module\Session;

use Magento\Framework\Session\Config as DefaultConfig;

class CustomConfig extends DefaultConfig
{
    public function setCookiePath($path, $default = null)
    {   
        parent::setCookiePath($path, $default);

        $path = $this->getCookiePath();

        //check and update path of cookie
        if (!preg_match('/SameSite/', $path)) {
            $path .= '; SameSite=None';
            $this->setOption('session.cookie_path', $path);
        }

        return $this;
    }
}

NOTE : replace namespace & module with your namespace and module.