Haaland and De bruyne have excellent chemistry. De bruyne is an excellent midfielder . Apart from assisting scores, he is also capable of scoring. With De bruyne in the squad we see a better performance from Haaland. In the last few matches we don't see a better performance from Haaland.
Manchester city's performance is still somewhat erratic. The main reason for this is that their midfield key players are not in the squad. Because of this guardiola has to change his match strategy. Gundagon, De bruyne and bernardo silva were Manchester city's mainstays last season. Silva and De Bruyne have been absent this season due to injuries and Gundagon has left the team. With Silva and De Bruyne in the squad, City's performance is likely to be more stable.
These two players have a central role in the strategy that Pep implements with his system. that's why, these two players have very good chemistry. but recently, Pep has developed another strategy IMO. now, every player is more involved when it comes to scoring goals, City is not just relying on Haaland and De Bruyne. we can even refer to the crucial match in the champions league last season, how City faced strong teams like against Madrid and Bayern.
At the beginning of this season City had a little problem with several of its players, De Buryne was hit by an injury, Bernardo Silva also had to be absent in the last two matches played by City. apart from that, Pep did not apply his flagship formation pattern. the departure of Gundohan, Mahrez, made Pep choose another option. that's why, it looks like City has decreased in performance. Naturally, because some of the players had to be absent in several matches. maybe, if Bernardo Silva, Stones, has been confirmed fit. Pep can implement the system the way he wants. after all the Champions League competition still has a time lag before it rolls out, Pep can give their young players the opportunity to grow even more. what is certain, in this competition City remains one of the favorite teams.
I can't really say they are the favourite in winning the UEFA Champions league as you said,they have their main players injured and sold,Debruyne,Mahrez,Gundogan and Bernando Silva all out,but Pep has really shown that he is a very good coach,being able to device a means to win a team like Newcastle who have shown that they are worth their position last season.It makes me feel like he is the best coach in the world,but I still think a more organised team like Arsenal will win City if they should meet again when those players are out injured.
The champions league will soon start,and with the transfer window still on,most teams have the chance to add quality players to their squad ahead of the competition which will kick-off in two weeks time,and untill the game starts,we can't just conclude that City is the favourite for the Tittle.