I strongly disagree with your assessment says that Arsenal already possesses a winning mentality. Arsenal has not won any Premier League titles for more 20 years. I believe, it is necessary for individuals to refrain from providing justifications for Arsenal's great performance and strong mentality. This is to prevent Arsenal from being overly confident in their current position; Consequently, I must acknowledge that Arsenal has demonstrated significant improvements since Arteta took the role of head coach. Both the defensive and attacking lines have made significant improvements, also this has been recorded from the statistic, which is saying arsenal has small gap goals conceded compared to the manchester city, but the consecutive defeats suffered by Arsenal against Manchester City, it clearly demonstrates that Arsenal lack winning mentality

Arteta is extremely dissatisfied with the performance of his attackers during the previous season. Arteta is currently considering bolstering Arsenal's offensive lineup, one of his effort to overhaul the striker position; Therefore, his decision is to add fresh strikers. There are several names being associated with Arsenal, but the club has not yet decided which striker to recruit.
In conclusion, arsenal is still yet far away from having a winning mentality.