I also read that PSG approached Zidane for the sole purpose so he can convince Mbappe to stay. PSG have some odd picks for managers, to me, the only one that made sense is Ancelotti. The rest looked like some odd trial they went with after relative success. You need a manager who knows how to play the style of players available, one that has the character to get the stars to come back and defend.
There's also a law of diminishing returns situation going on in PSG. So many stars up front doesn't mean more goals for each, maybe more in total, but less for each. If it was up to me, I would replace Mbappe with a winger with a high work rate defensively and move Messi central then play a more possession-styled gameplay.