Possible solution for multiple where: in GraphQL and Wordpress

function.php

<?php
// Register extra types
add_action('graphql_register_types', function () {

    $customposttype_graphql_single_name = “MyCustomPostType”;

    register_graphql_field('RootQueryTo' . $customposttype_graphql_single_name . 'ConnectionWhereArgs', 'postObjectIdTWO', [
        'type' => 'ID',
        'description' => __('The ID of the post object to filter by', 'your-textdomain'),
    ]);
})

add_filter('graphql_post_object_connection_query_args', function ($query_args, $source, $args, $context, $info) {

    $post_object_id = $args['where']['postObjectId'];
    $post_object_id_TWO = $args['where']['postObjectIdTWO'];

    if (isset($post_object_id) && isset($post_object_id_TWO)) {
        $query_args['meta_query'] = [
            [
                'key' => 'myCustomField',
                'value' => $post_object_id,
                'compare' => '='
            ],
            [
                'key' => 'myCustomFieldTWO',
                'value' => $post_object_id_TWO,
                'compare' => '='
            ],
        ];
    }

    return $query_args;
}, 10, 5);

query.gql

query GetMyCustomPostType {
  MyCustomPostType(where: {postObjectId: “123”, postObjectIdTWO: “456”}) {
    nodes {
      title
    }
  }
}