All teams lose points sometimes it's inevitable (even City have lost 2 points more than Arsenal at the moment) and it's impossible to predict when it will happen. In the next round, Arsenal play with Nottingham Forest - the worst team in the league, which it is ahead of by almost 20 points. Most likely this game will be very convenient for Arsenal to regain their confidence and score a lot of goals. Nottingham Forest concede an average of 2 goals per game and Arsenal have the second attack in the league - a big score in this game is extremely likely.
Yes indeed, even the top teams that dominate the league from season to season are still likely to be held to a draw and also defeated. So yes, a result like this is certainly a reasonable result, moreover Arsenal also just got a very good performance at the beginning of this season which of course any result will still happen and it can happen randomly at any time and also by any team.
At least Arsenal can still rotate their players well because after against Nottingham, Arsenal will play away against Chelsea in the next match which of course won't be easy. Even though, for example, in the end, Arsenal did not win the title, but at least Arsenal have proven the revival they managed to do and will return to play in the Champions League next season.
Oh, if the game against Nottingham Forest is supposed to be a rest, then the game against Chelsea will be a big challenge. Moreover, between these games there will still be a game with Zurich, so the schedule is quite tense. Judging by the latest games, Arsenal have some problems with the implementation of chances, even now, if you look at the statistics, they dominate the game with PSV, but at the same time the score is 0-2 in favor of PSV. This game doesn't have much tournament value for Arsenal, but it will probably be a reason for Arteta to try to change something.