You can see the incident in question here at 4:27:
You cannot do flicks and kick-ups near your own goal, with your back to goal, and lose the ball, immediately handing the opposition a chance. You just cannot do this at any level of football. It's not indicative of a lack of effort, it shows that his mentality at that time was "I'm Paul Pogba. I'm a superstar. I can do whatever I want".
And that was on top of a display where he just strolled around, clearly not giving 100% effort. And he was at fault for failing to mark properly for a set-piece on one of the goals.
As I said previously, if it was my money going into the club, I would feel a bit piqued that Pogba played like that a few weeks ago, but has now suddenly decided that he's motivated again. I don't doubt his ability as a footballer; that is not in question.