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\CustomerGraphQl\Model\Resolver\IsEmailAvailable">
        <plugin name="CustomerGraphQl"
                type="Buffetti\FormHelper\Plugin\IsEmailAvaibleBefore"/>
    </type>
    <type name="Magento\Customer\Model\CustomerRegistry">
        <plugin name="CustomerRegistryOverrideAfter"
                type="Buffetti\FormHelper\Plugin\CustomerRegistryOverride"
                sortOrder="99"/>
    </type>
</config>