I think they don't want to sell Mbappe but PSG wants to somehow earn more money from Mbappe than this by extending his contract and selling him for more money, or even if they wanted to keep Mappe in the club for a longer period of time and benefit from the player who can help Enrique achieve his goals in the club.
Keeping mbappe till his contract gonna be running out will give no benefits for the club. PSG still has no chance to win UCL next season. The fact that if PSG prefers to sell him for big amounts of money to get back their investment rather than try to hold him till his contract is gonna end.
PSG can reinvest its money from selling mbappe again to buy and build the new team. that will give more benefit for the club compared with keeping him til the end. Mbappe doesn't wanna extend his contract which is a big loss for PSG with its very big investment to him.
PSG is thinking a way smarter to sell mbappe, get back its investment, reinvest it again. The club shall try to sell him as soon as possible no matter what happened with mbappe. Getting money is the main priority for the club right now.
Enrique will be thinking so hard about how to sell mbappe to the another club. PSG's chairman was also sending another message for mbappe. He feels that if mbappe was very selfish while khelaifi reminds him again not to be so selfish.
Mbappe's personality is very bad. It's become a negative side from mbappe. It will be far better if mbappe can put respect to the PSG.