Their culture are different, Manchester City's culture is play for team regardless there's a star player or not. But Manchester United's culture is play with ego and seniority, since both Bruno and Rashford are old players, they deserved to get ball than the striker.
Hojlund is just a junior player, maybe Bruno is working together with Rashford in order to destroy Hojlund and Rashford will back as a pure striker.
Clearly this is what Plays out with Manchester united most of the time, they play with so much ego and tend to give few or no privilege to younger or junior players and this culture of theirs is really telling on their performance so far because these young talents become less optimal.
Bruno Fernandes happens to be one who exhibits so much of this attitude, some times I think he places his personal interest over that of the team thereby reducing their chances of winning in some of the match, hojlund is a very good player which if such team spirit found in Manchester city could be replicated at old Trafford, he will definitely thrive way beyond his current state but then the bigger boys still wants all the glory to themselves.