Pep Guardiola must take advantage of the January transfer market if he wants to change or make his team rise and Manchester City management must also fully support it, otherwise I think their slump will be even deeper.
It has been only Haaland in striking for them this season, he needs another striking option just as he needs new defensive options and another option in defensive midfield. Manchester City are slowly drifting far from any chance to defend their title again, and Chelsea although the coach refuses to admit it are shockingly the title contenders this season, currently in the race with Liverpool. If Chelsea do not face problems later with injuries, or fatigue, they can actually win this season.
Haaland unfortunately continues to show that he does his job well, but he is not one to make a difference. He has incredible stats but I'm unlikely to see the "things were going badly but Haaland turned the game around" highlights that you can find for most top players (especially strikers).