Relationships in Custom REST API Endpoint

Hi -

I'm creating a custom REST endpoint and I'm having trouble populating Metabox Fields.

website returns true/false and cities is null.

Thanks for your help!

if( !class_exists( 'toAPI' ) ) {

    class toAPI {
      function __construct() {
        add_action( 'rest_api_init', [$this, 'init'] );
      }
    
      function init() {
        register_rest_route( 'to/v1', '/destinations', [
          'methods' => 'GET',
          'callback' => [$this, 'get_destinations'],
        ] );
    
        }
    
      // Get recent destinations
      function get_destinations( $params ) {
        $destinations =  get_posts( [
          'post_type' => 'destinations',
          'posts_per_page' => 10
        ] );
    
        foreach( $destinations as &$d ) {
          $d->thumbnail = get_the_post_thumbnail_url( $d->ID );
          $d->website = rwmb_meta( 'website' );
          $d->cities = MB_Relationships_API::get_connected( [
                'id'   => 'destination-city',
                'to' => $d->ID, // You can pass object ID or full object
            ] );
            foreach ( $d->cities as &$c ) {
                $c->post_title;
                $c->id;
            }
        }
    
        return $destinations;
      }
    
    
    }
    
    new toAPI();
    }