WooCommerce-API: Filtering Orders with Custom Field

I retrieve orders from WooCommerce using the Wordpress API. Wordpress and Woo are up to date. The retrieval takes place via "/wp-json/wc/v3/orders".

Now I want to filter the retrieval of these orders by a custom field (which is also displayed below "meta_data"). Unfortunately the custom fields are not available as get parameters. The parameter "?filter" has not been available for some time. I don't want to use the plugin that brings it back.

Can you tell me which hook I have to use how to use the custom fields (or the special custom field) as a filter attribute?

With this code I managed to restrict pages with custom fields. I need the same for WooCommerce orders. Unfortunately this code doesn't work when I use "add_filter( 'rest_shop_order_query', 'post_meta_request_params', 99, 2 )".

if( ! function_exists( 'post_meta_request_params' ) ) :
    function post_meta_request_params( $args, $request )
    {
        $args += array(
            'meta_key'   => $request['meta_key'],
            'meta_value' => $request['meta_value'],
            'meta_query' => $request['meta_query'],
        );
        return $args;
    }
    add_filter( 'rest_post_query', 'post_meta_request_params', 99, 2 );

endif;