I think City being a great team plays a good role on this as well, Haaland is amazing but you can't put Haaland at a team like Everton and expect him to get the most goals in a season, that would not work, they do not get enough scoring possibilities.
Of course you are correct Haaland is a very good player, he is one of the first Bundesliga player to come English league and perform the way he does, he is actually one of the best striker on premier league that scores almost all there matches.
There is no doubt that Haaland is one of the best strikers in the Premier League if not the best because he score plenty goals that people never expect in his first season in the Premier League, but this season, he has played some matches without scoring goals due to the absence of KDB in Manchester City's midfield.
Yeah that's true Haaland has not been scoring much goals from there past matches even on that there match against Arsenal team he was finding it difficult to cope and since most of the clubs knows that he is a good striker and doesn't joke with scoring goals they always make sure to tackle him in such a way that he will find it difficult to perform that's exactly what is happening to him right now.
Although if Kevin de Bruyne were to be on there games it would have been an easy one for Haaland to keep scoring his goals because most of his patterns is mostly based on team work built by Kevin de Bruyne so I believe his absence is really affecting Haaland.