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.
Slot took over that position after a successful Klopp era and he began under huge pressure but he managed his job well and even impressively won Premier League title with Liverpool in his first season there. In this season, Liverpool already started well and they are ready to defend their title even there are many clubs that want to take it over from Liverpool.
I understand why they say that, as we know Manchester City's performance is inconsistent so some people are doubtful and not sure they can compete with Arsenal and Liverpool well they don't realize that we can't conclude just by looking at a few matches. I think Manchester City is still a threat to those who want to compete at the top of the standings.
If we check the Sportsbook predictions then we can see Manchester City is in 3rd place as the favorite team for the title and even Chelsea are under them. As I said before everything will be clearer as we get closer to the middle of the season so there we will see which teams have the greatest potential to win the league.

Arsenal seem to not be creative and powerful enough in attacks while Manchester City still struggle to improve their squad and there is still existence of their tactical and systematic problems since the last season. Cheslea can be a most intersting underdog in title race and I don't trust either Arsenal or Manchester City can beat Liverpool but if Chelsea can make big surprise, Premier League title competition will be interesting and unpredictable in this season.