Ii also observed that too. I don't know whaut Vinicius was saying after he gave Mbappe the assist. It shows that both players are in good terma and have accepted to play along side with each other without any ego. I agree with you that if they can cooperate together in the frontline, we will see the best combination of these two players and more goals than before.
Vinicius has understood very well that if he continues his haughty behavior in the Madrid squad, he will be out of the squad. Madrid has always been a strong as a team. They do not want to be rely on any particular player. So if Vini is arrogant, then its effect will be seen in Madrid's overall gameplay and Madrid's attacking performance will become weak. If this happens, the Madrid management will definitely decide to sell Vini. And that is why now we can see the friendly relationship between Mbappe and Vini.
He is arrogant and effective which a fact the coach needs to work with and if there is reason to play him and the result will come then i dont see why he should be bench during the game.