newsupernova/vendor/magento/module-grouped-product/etc/config.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <checkout>
            <cart>
                <grouped_product_image>itself</grouped_product_image>
            </cart>
        </checkout>
    </default>
</config>