Vinicius and Bellingham can play well together, last season showed that, but Mbappe is clearly falling out of the team game, he's been doing about the same thing for the last few matches. Like in the last match against Barcelona Mbappe opens up, runs down the right flank and shoots at goal and Mignan also knew it well and therefore had no problem reflecting his shots, so apparently Ancelotti has a difficult choice to make.
On the other hand Mbappe is not the first star player who, when moving from one top club to another, failed to show all that he is capable of and you can remember Coutinho, who after coming to Barcelona almost ended his soccer career or Neymar, who on the contrary, when moving from Basrelona to PSG, gradually played worse and worse, got injured and eventually left for the Saudi championship.