Brighton is like another version of Nottingham Forest, but unlike them, they need to feared because of how well the players play and how any of them can score. Aaron Wan-Bissaka will have to keep Kaoru Mitoma calm min the game because he can become a lot of trouble for the suffering Manchester United Defense. Diogo Dalot will have to do the same at the other side against March, and in middle Maguire will face the pressure of an experienced Danny Welbeck.
Brighton is one of the teams that is able to make it difficult for big teams to achieve maximum results and if you look at their current performance it is very consistent. They could beat Manchester United quite easily considering the many problems Erik Ten Hag is currently facing. The three Brighton players you mentioned are devastating for Manchester United's defense and especially Karou Mitoma will definitely be very difficult to stop because he has speed and good dribbling.
Yeah, Manchester United does have some internal problems but we have to consider them playing at home it is very difficult to beat Manchester at home, maybe you still remember when Manchester United played against Nottingham at that time they were 2 goals behind but managed to make a comeback 3-2 and win, it is proof that Manchester United has more strength when playing at home and that's why I'm not sure Brighton can win easily, the worst thing that can happen is a draw imo.