Why are we running a loop of CPT twice

gistfile1.txt

add_action('rest_api_init', function () {

    // Path to the config file
    $config_path = plugin_dir_path(__FILE__) . '../admin_pages/site.json';
    $config = json_decode(file_get_contents($config_path), true);

    $post_types = get_post_types(array('public' => true, '_builtin' => false), 'objects');
    $order_fields = array();

    // Collect order fields from CPT config
    foreach ($config as $cpt) {
        if (isset($cpt['fields'])) {
            foreach ($cpt['fields'] as $field) {
                if ($field['type'] === 'order') {
                    $order_fields[$field['id']] = $field['id'];
                }
            }
        }
    }

    // Register a REST route for each CPT
    foreach ($post_types as $post_type) {
        $type_slug = $post_type->rest_base ? $post_type->rest_base : $post_type->name;

        foreach ($order_fields as $field_id) {
            // Register a REST route for each order field
            register_rest_route('wp/v2', "/{$type_slug}_{$field_id}/", array(
                'methods' => 'POST',
                'callback' => function (WP_REST_Request $request) use ($field_id) {
                    return update_post_order_with_meta($request, $field_id);
                },
                'args' => array(
                    'itemsToOrder' => array(
                        'required' => true,
                        'validate_callback' => function ($param, $request, $key) {
                            return is_array($param);
                        },
                    ),
                    'parent' => array(
                        'required' => false,
                    ),
                ),
            ));
        }
    }
});