src/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\Checkout\Model\Session">
<plugin name="integernet_addtocartgraphql_forceguestcart"
type="IntegerNet\AddToCartGraphQl\Plugin\ForceGuestCart" sortOrder="10"/>
</type>
</config>