THE LAST SCENE BETWEEN MASTER FU AND MARINETTE TRANSLATION
The episode ended a few minutes ago so this is what I remember from the conversation.
Basically Master Fu explained what happen when ladybug’s earrings and chat noir’s ring are used together. It gave absolute power who can grant a wish.
Marinette then ask why they don’t used them to stop war or eradicate poverty.
So listen master fu explain that when we make a wish something in return is taken. He gives the example of Markov who wanted to become human. If markov had realize his vow to become human then someone else would have lost his humanity.
Edit: The episode is already on tf1 site so I rewatched the scene and master fu also talk about a special invocation. You need to know the invocation to be able to use the power of the miraculouses. He also talk about how the power shapes the reality and the universe must keep its balance.

