By the way we didn't see Mbappe in this game. As these are his last days at PSG I would expect him to take part in the remaining games. I wonder whether he didn't want it or Luis Enrique didn't want to.
Mbappe has confirmed that this season is his last with PSG and he will leave at the end of the season, but as far as I know mbappe still has the responsibility for him to play with PSG until the end of the season so it seems that Enrique is preparing Mbappe for his last match with PSG when he faces Lyon in the French Cup final, For now PSG no longer need points in the remaining Ligue 1 matches so it is very natural that Luis Enrique dropped almost all of his reserve players in the match because indeed the game against Nice is no longer a priority for PSG.
At the moment Nice only have a chance to play in the Europa League next season, but after all their failures this season of course playing in Europe will be a great achievement for them, even if Nice can reach the Champions League play-offs, of course I am not sure they can get through it with the performance they are now, this season Nice can end the season ranked 5th and certainly that's not a bad thing with the inconsistency they have had so far in Ligue 1.