Last season, if I remember correctly, many people believed in Manchester City because KDB, who always performed well, supplied the ball to Sterling, Mahrez and Gabriel, but in the end, they all fell silent because they had to be disappointed again

Don't be too confident now even though it can't be denied that Haaland is a pretty great goal machine but this is a competition with a great team and we can't know who they will be playing against when they are in the knockout phase because for the group phase it's clear they will definitely pass.
Well, yes we can not assume that the championship for the Premier League will be for Man City this season, just because of Erling Halland's addition to the squad, but we can not take out the fact they are doing great now that Erling Halland is on the team, and we are still in the start of the season for both Premier League and UEFA champion league, so there is a huge chance for Manchester City to get it this time,
For the Premier League it may still be possible to go back to back for the third time but the Champions League is definitely something different. Regardless of how good Haaland is at the moment, still for Champions League City there is still a lot for them to do especially in this league they are challengers.
This is not just an assumption but the fact is that there are still several big teams that are candidates for the Champions League and City is one of the clubs that have a chance to win the title.