I'm not even trying to be a dick in saying this because I don't hold anything against Hojlund but, although a lot gets said about him needing a loan (which I don't entirely disagree with), I equally think it's entirely feasible that he just doesn't have what it takes to make it here.
I quite agree with people who aren't overwhelmingly impressed by Zirkzee's performances thus far either but the difference is at least with him I think there is a functional if somewhat unimpressive attacking unit you can build with him up front. Although he's entirely lacking the goal threat you'd expect from a Premier League striker, he's actually quite good at holding the ball up and with the right players around him he's smart enough to create chances using this.
Hojlund, as shit as it is to say, just isn't really offering anything right now. I'm not sure it's really an attitude thing because he does try. He just doesn't have the nous to outmaneuver even the lowest level Premier League centre backs, and doesn't have the technical ability to be in anyway useful in the build-up either.
The reason, though, that I bring up that he may just not have what it takes is that he was signed off the back of essentially half a season's worth of strong performances for Atalanta. Now, development isn't linear, and at Hojlund's age it'd be unfair to just entirely write him off but what I would say is that it wouldn't exactly be out of character for the godawful era of Arnold, Murtough and Ten Hag transfer windows for us to have spent an inordinate amount of money on a player who just doesn't have it.