It is not only because of the return of KDB, City usually get stronger when the season is approaching the run-in period and that's what is happening now and it is scary for the rest of the league. With Haaland, Stones and Akanji all set to return soon, City would soon be able to boast of a complete squad and they'll be ready to defend their crown.
Having said that, let us not forget about Liverpool who are going about their business without any noise or fuss, too many people didn't consider Liverpool at the start of the season, but now they are taking them serious and IMO if City don't win the league, Liverpool will.
This is true sometimes but not applicable in all situations, they win that match because Newcastle was weak and they are also trying to trying to save their home from Manchester City humiliation. Newcastle was even the first team to retaliate with a goal after Manchester city gave lead them with one and then added another goal to lead with 2 goals but Rodri balance the game when they are just about to go for 15 minutes break.
Manchester city is clearly trying to get ahead of other teams just like they did last season. If Liverpool loss any match from henceforth, they will become even with point and I don't think Liverpool is ready for such humiliation, they are going to fight because even Manchester City squad are not that completed to achieve that on their own. It might took Haaland another 3 weeks before he return fully for the club and matches would have been played before then.