steam works in that way that it says you are currently playing arma 3 when you have the arma 3 launcher open.
While that isn't inherently an issue I think it's an issue that the launcher doesn't close itself automatically when you start the game. I don't think there is any reason anyways why it should stay open.
That comes to a problem when you close the game but not the arma 3 launcher and it still says on your steam profile that you are playing arma 3.
Several times have I forgotten to close it.
That might just be my opinion on that matter but it's bothering me.
I see only 2 possible solutions to that "issue":
1.: Make steam not register the arma 3 launcher as playing arma 3. I don't know if that is even feasible or if it is intended like that by developers in that way.
2.: Make the launcher simply close itself when you start the game.