At first I thought like you. But it turned out that I was wrong, Gabriel Jesus is not as good as Haaland, so Man City's strength increased many times after Haaland came. Haaland became a striker who needed a lot of players to stop him. This is because he is bigger and stronger. Unlike Jesus, he is good but not as good as Haaland. Haaland was able to attract many players to stop his movement. So Haaland opens up a lot of space for a second striker or midfielder to make a goal-bound shot from outside the box. It worked during the FA Cup final.
I still think Manchester city doesn’t depend wholly on the abilities of Haaland as a striker to score goals. No doubt, Haaland is a very talented striker and Manchester City’s strength may have increased a bit with him on the squad. He’s a big and energetic striker who’s also moves quickly and opens up beautifully for passes or crosses from other teammates to score goals.
I wouldn’t say Gabriel Jesus is not as good as Haaland. Gabriel Jesus is a more experienced player than Haaland. Haaland has his youthful energy as well as his height and build and he uses all that to the best of his ability.