It's not about making mistakes, mistakes are acceptable, but about the negative habits and tendencies in his game that need to be weeded out. Even today, with a good performance, these tendencies and habits were obvious.
He brings almost zero defensive contribution.
He's not effective in getting involved in build-up, but choosing to wait for the ball to get to him and then attacking the defense.
He has selfish tendencies.
He has a poor habit of taking one touch too many, or one dribble too many, and getting himself in poor positions as result.
He has plenty of talent, talent has never been the problem, but he has too many rough edges to his game still that he needs to polish up. He's the clear case of a player who got by in the lower divisions purely off his immense talent, and as a result, has plenty of holes in his games that need to be filled for the top level.
Munir is younger, yet is far more polished than him in all these aspects.