It is obvious that PSG have never sold any of their stars since QSI acquired the ownership of the club, but this is to their disadvantage. In Qatar, people are sick of Kylian Mbappé's attitude, therefore they want to reap the biggest rewards in order to restore balance to the Financial Fair Play's ravaged books. If the "7" was sold to Real Madrid for more than 200 million euros, the club would regain much-needed flexibility to carry out the restructuring that Luis Enrique intends to perform.
Another key factor is related to the future of Neymar. He seemed more outside than inside, but his relationship with the Spaniard is so positive that he could be the key piece of PSG for the next few seasons once Kylian leaves the Parisian ship. At Real Madrid they expect updates very soon.