The trolls just want to make something look funny so that their page or channel or whatever they have gets views. It is hard to do when you are the one playing on the pitch. And if the team loses, Haaland is obviously not the only one to blame. He has been performing well. Even though it is not something very special I still think he is performing well. And he should not be the only one responsible for losing at all. I would actually argue about what the other players were doing. A player can actually have one match in which he does not play well. That does not mean he is a bad player and that also doesn't mean he is the only one responsible for the loss.
Well fans have the right to say whatever pleases them but the fact still remains that Manchester City are still very strong contenders of the league, and the fact they've lost 2 EPL matches consecutively doesn't stop them from winning the league, because last season they lost several games but still won the EPL trophy, I think they're in their unlucky days and would bounce back sooner.
Maybe when they do we'll begin to see Haaland scoring braces or hat-trick in their upcoming matches, I don't think Haalands performance is bad, he's still the player with the highest goals this season just that luck didn't shine on him against Arsenal, and the defence really tried in marking him well and gave him little time to create good chances, however I believe when the player that understands him better (Debruyne) gets back we'll begin to see his best again.