Perhaps the loss of Kevin De Bruyne is one of the reasons for Manchester City's decline in performance.
The player hasn't looked like a key player after a long injury layoff, but he's nonetheless a key player who consistently supports Erling Haaland in scoring the winning goals in every match.
What's happening now is really just about getting the right players to achieve more consistent performance.
Kevin De Bruyn barely played in played regular football in the last couple of season at Manchester City yet, in the season before the last one, they won the English Premier League. I think there is more to Manchester City's woes than just players or maybe the oppositions has got harder, and they are now well versed with Guardiola Ball.
Remember how Klopp's Liverpool performed vs When Arne Slot took over? He barely signed anyone, and yet they were so impressive. Sometimes, all it takes to change is just the coach.