Hopefully he doesn't stay off beyond two weeks because looking at Odegaard predicament it is potentially going to distort Arteta's initial plans for the time being, and many arsenal fans are worried knowing that their next two fixtures are their major rivals in the league Tottenham Hotspur and Manchester City, meanwhile Atlanta also awaits in the Champions League and all the matches are to be played this September.
It seems like one of the problems that many clubs are experiencing right now is injuries. Yes, many main players of clubs are injured, plus in the UEFA Nation match, there are several main players of EPL who are also experiencing it.
The last one is Nathan Ake who just got injured while defending his national team:

Man City will have to play without the defender, at least for the next two games against Brentford in the EPL and also Inter Milan in the UCL. Also, it is still unknown how long he will undergo the treatment and recovery process.