A lot of this is fair I think. There's definitely more he could be doing in terms of making more creative runs, looking to separate from CB's and play in space more rather than automatically get drawn into a fight for the ball, and be quicker to pull the trigger when he has a chance at goal etc. But clearly the service he's getting isn't particularly good, there's a lack of overall cohesion and chemistry from an attacking sense in the new system, and he's understandably low on confidence given results and the general negative sentiment surrounding the club at the moment.
It's so blindingly obvious that there are these more deep-rooted problems that are heavily contributing towards the lack of goals and towards his below-par performance levels at the moment, yet rather than use logic and come to that same conclusion, it seems like a large swathe of United fans have instead decided he's just plain shit, will never be good enough and should be sold. This despite the fact that he clearly showed a lot of promise at Atlanta and in his debut season at United to the point most fans were fully expecting him to take a step forward at the start of this season and go from 10 PL goals to 15-20.
People love to compare him to the likes of Gyokeres, Osimhen, Kolo Muani who've all been linked recently or other CF's who've gone for a similar amount of money recently like Isak or Solanke and bemoan that they're much better players, but all of those are 3, 4, 5 years older and were either playing at the same or a lower level than Hojlund at the same age. He's basically playing exactly as you would expect a 21 year old CF to be playing... showing glimpses and potential of being borderline elite but lacking the level of consistency, confidence and instincts that naturally come with experience.
I think the fact we've had the likes of Messi, Haaland, Mbappe, Rooney, even Aguero and Torres who were consistently scoring most weeks in top leagues at age of 18, 19, 20 has pulled the wool over our eyes a bit and made us think that's typical... but there's a whole list of this generations top goalscorers / CF's such as Henry, Kane, Suarez, Lewandowski, RVP, RVN, Shevchenko, Eto'o, Benzema, David Villa, Drogba etc who didn't find that level of consistent performance and goals until they were older than Hojlund is now.
I totally get wanting to sign another CF who is a bit further along in their development and maybe better suited to helping the team right now, but that doesn't mean Hojlund should be completely written-off which seems to be an increasingly popular narrative.