I was told by somebody pretty well connected that Lookman was told by Koeman the end of the transfer window to pack his bags.
It sounded like Lookman and Mirallas both questioned Koeman's use of them and were told where to go.
I'm not sure whether it's Koeman's job to say that to players though. We have a director of football who you would hope deals with this kind of thing, Koeman is there to make the best use of whatever tools the club provides for him. Of course if Mirallas, who is an experienced member of the squad, shows dissent then that's a different matter but to tell a young highly rated boy to pack his bags I'd be very surprised if this was true.