This is broken.

Anchestors.php

<?php

namespace Valu\Sakke\GraphQL;

use WPGraphQL\AppContext;
use GraphQL\Type\Definition\ResolveInfo;
use GraphQL\Deferred;

/**
 * Basing on WPGraphQL v0.7
 * https://github.com/wp-graphql/wp-graphql/blob/e87a992cba20eefa6ffdd433cbdfaf0c477797b0%5E/src/Type/InterfaceType/HierarchicalContentNode.php#L18-L45
 */
class Anchestors {
    static function init() {
        add_action('graphql_register_types', [self::class, '__action_graphql_register_types'] );
    }

    static function  __action_graphql_register_types() {


        register_graphql_field('HierarchicalContentNode', 'legacyAnchestors', [
            'type'        => [
                'list_of' => 'ContentNode',
            ],
            'description' => esc_html__( 'Ancestors of the object', 'wp-graphql' ),
            'args'        => [
                'types' => [
                    'type'        => [
                        'list_of' => 'ContentTypeEnum',
                    ],
                    'description' => __( 'The types of ancestors to check for. Defaults to the same type as the current object', 'wp-graphql' ),
                ],
            ],
            'resolve'     => function( $source, $args, AppContext $context, ResolveInfo $info ) {
                $ancestor_ids = get_ancestors( $source->ID, $source->post_type );
                if ( empty( $ancestor_ids ) || ! is_array( $ancestor_ids ) ) {
                    return null;
                }

                $context->getLoader( 'post_object' )->buffer( $ancestor_ids );

                return new Deferred(
                    function() use ( $context, $ancestor_ids ) {
                        // @codingStandardsIgnoreLine.
                        return $context->getLoader( 'post_object' )->loadMany( $ancestor_ids );
                    }
                );
            },
        ] );
    }
}