There is some news about Neymar leaving PSG but his destination of him is still unknown, all we know about Neymar is he can be a good option for any team but because of his playing style he gets injured time after time which can be bad for any team but this cant be a weakness of this player that's all because of his playing style.
All this news is speculation because in March Neymar committed his future to PSG. His options will be limited by his constant injury problems because no club will want to spend big on such a player. But the Brazilian striker still has quality and goodwill. Any club that he moves to will also make money from other means because Neymar is still a big name in world football 
Paris Saint Germain fans watched those magical moments of Lionel Messi in Barcelona shirt, they saw him single handedly tear opposing teams apart in his Barcelona days and they have also seen him win the titles for Argentina national team. And that's why they think he's not playing for the club the way he ought to.
Their frustration against Messi took a leap when Messi captained Argentina defeated France in last year's world cup final with Lionel Messi scoring two goals and also converting his own penalty during the shootouts. The good thing is that Barcelona is calling for his services at the moment so it's better he goes back to where he's loved and enjoy football once again
I don't think Messi has underperformed in PSG. Considering his age, he has contributed immensely to the success of the club. The only reason why the fans or management thinks that he has not done enough was that they failed to win the Champions League this season. The club would have been singing praise songs about him if they had been crown the champions of Europe.