Well it's obvious that the absence of two players Kelvin Debruyne and Rodi has contributed to their poor performance and this should let Pep Guardiola to know that the team still needs strengthening,
Yes mate I think Manchester city are suffering from extreme injury problems and the match against arsenal exposed how even them can fall without the right players, they are missing Kevin and some players are playing the wrong roles or aren't playing in their natural position.
One of the biggest mistakes they made was to sell some very important players and they didn't improve their midfield
I guess you are talking about players like Gundogan which was replaced by Kovacic from Chelsea. Every strong team must have a weakness and that of Manchester City was noticed and that was used to take advantage of them. It shows that they can’t do without some certain players even if they substitute with others. Lack of De Brune in the squad have not been showing too much when they have been playing other teams but now that they face a big team like Arsenal, they have both miss out of the game with De Brune and Rodri. This is just a game and it happens to anyone it wishes at some point and I think Manchester City won’t be weakened by this not to do better in their next match in the league.
Undoubtedly, Kelvin De Bruyne and his Manchester City teammate Rodri were two of the most important members of the Pep Guardiola team that won the treble last season and that why since the sustained injury this season, Manchester City hasn't been getting good results like they were getting last season.
The absence of Kelvin De Bruyne also has significantly affected Erling Haaland's goalscoring abilities as the Belgian was always assisting Haaland for most of his goals last season. Rodri's injury isn't as serious as De Bruyne's injury an would return to action very soon.
We must admit that Kevin De Bruyne and Rodri are two indispensable factors in Pep Guardiola's tactics. Especially De Bruyne, he is the center of Man City. They are facing difficulties after 2 consecutive defeats in the Premier League. However, their good players like Rodri, John Stones, and Kevin De Bruyne are about to return after injuries and suspensions. Perhaps Man City will once again send chills down their opponents' spines. The good news is that Rodri's suspension has ended, and Man City will have his services in the upcoming matches. As you said, De Bruyne's return will be a real boost for the team. The person who will benefit the most from De Bruyne's return is Erling Haaland, the striker seriously declining due to De Bruyne's absence. De Bruyne's can provide Haaland with the best passes.