This season the journey will not be the same as last season so any team will have to fight differently, both in the UCL and in domestic leagues such as the Premier League. The return of De Bruyne and Doku could indeed have a good impact on the Manchester City team, but Haaland's absence also has other effects on the Manchester City team. Currently, all teams in the Premier League are under even more pressure when one of their mainstay players is absent because in the second half of the season all teams will try to get more wins.
I've never heard of Haaland being seriously injured. Just a few injuries that didn't keep Haaland out for long. There are several injuries that I've heard of-ankle injuries, thigh injuries, muscle injuries, pelvic, knee, and ligament injuries. At the moment, I'm not sure what kind of injury he has. I probably don't even know if he's injured at the moment. But when I read the news, he's starting to train with small activities.
Source:
https://www.standard.co.uk/sport/football/man-city-injury-update-haaland-silva-stones-latest-news-return-dates-b1130919.html