Malacia is a player who is associated with Feyenoord, not Manchester United. As of my last update in September 2021, Malacia was a Dutch left-back playing for Feyenoord in the Eredivisie.

If there have been recent developments or transfers involving Malacia moving to Manchester United and playing for their U21 team, I would recommend checking the latest news sources for the most up-to-date information.

If you need any more assistance or clarification on this topic, feel free to provide additional details!