If Kevin De Bruyne was the reason for the Man City team's decline in performance, now he is back and let's wait and see how Kevin De Bruyne contributes to the team after the long injury he suffered.
I think the reality is that since KDB was injured, Manchester City's game has not been good in attack, so that's why we will see how Manchester City really is when he actually plays again after his injury. Luckily, Manchester City still qualified for the last 16 of the UCL during KDB's absence. In order to defend the UCL title this season, of course Guardiola also wants his best injured players to recover quickly and play.
At least being able to reach the UCL final is Manchester City's main target to win back the title this season. I also hope that with KDB playing again, Manchester City can really perform better than before and I really can't wait to see that where KDB is already in the reserves. who is ready to play whenever Guardiola wants. At least he was played in the first leg meeting against Copenhagen in order to achieve a landslide victory.
Even without Kevin De Bruyne in Manchester City squad, they will qualify to the round of sixteen because the team is not a bad team that solely depend on only one player. I will agree with everyone that without Kevin De Bruyne, their performance is not as last season and they lose some matches they are supposed to win due to his absence, and I will also agree with you if you said that he is a player that if Manchester City play without him, they might not win the Premier League as well as Champions League.