I think City's biggest weakness was their attack. We have seen the irregular performance of the attacking players. If I am asked what City needs to perform well next season, then I would say that City first needs a worthy replacement for De Bruyne. De Bruyne was one of the most important players for City. If this player is not found, City's midfield will not be stable.
City also needs to replace Haaland. If Haaland gets injured, City's performance will become erratic. Guardiola will definitely have to pay attention to this aspect. After these two changes, Guardiola will have to take necessary steps to further strengthen City's defense.
Manchester City had a squad overhaul last summer but pep guardiola biggest mistake was not truly replacing those players. The reliable players like Rodri, De Bruyne got injured early and this made the squad depleted as there weren’t any creativity coming from the midfield and this affected Halaand and other attackers too. So for me the immediate resolution should be the midfield which is the area Pep is trying to strengthen at the moment. The arrival of Cherki and Tijjani will help give Manchester City depth in two vital positions which is the attacking midfield position and the Defensive midfield position which to me is very good replacement.
Pep also added a left back because city defense were obviously shipping in goals like a basket and it affected them. I Will also agree that city can actually add a striker even though a low budget one to help fill up for Halaand during his drought period or when he is injured but Manchester are capable of playing without striker though