I also won't be surprised if they end up not even winning any trophy too. Arsenal no doubt have played really well this season and also have being somehow consistent but one thing about this club is that they always flinch when the league is about to end. The reason why I feel the pressure might get to them is because of the two competition they are currently playing which is the champions league and premier league, it's an enormous amount of discipline and skills to manage the playing capability when performing to win or secure two trophies.
What you are saying is true because it has happened to Arsenal last season when they lost the opportunity they had on wining the premier League last season to Manchester City and they almost repeated the same thing again this season if not that they were able to regain there performance when the league is still on, however I don't think Arsenal playing on the two leagues will affect them because right now there focus is not really on the champions League because they know fully well that there are more quality clubs on the race for that trophy, so there interest now is on the premier League.
Arsenal had a mistake last season when they failed to win the Premier League title. Despite their hard work, everyone expected Arsenal to win the league last season, but they did not. I believe Arteta learned his lesson from the mistake they had last season, that's why he gathered more players this season, since the players they had last season are not strong enough to compete for the championship. We shouldn't judge Arsenal based on their mistakes last season, I'm expecting something different this season.
Arsenal have not lost a single Premier League game in 2024, we may be surprised at the end of the season if Arsenal wins a trophy, their performance has been much better than last season. I also don't think Arsenal will struggle to compete in two competitions, they won't become weak since they have so many players to replace on when others are weak. We are only scared of Arsenal since they did not win the league previous season. Manchester City and Liverpool are also competing in other competitions, it is hard to predict if this will affect their performance. I think the best thing for Arteta is to focus on their Premier League games, as the Champions League will be very tough.