Where do you get such informations?! Are they even valid, do you have anyone from/in the dressing room leaking information to you?! If you don't then, these assumptions makes zero sense for real. There's nothing going down between these players. I have only seen rumours of Vinicius Jr wanting his salary toped as Kylian Mbappe, asides that, nothing. I have always said it before now, people who hate Kylian Mbappe needs fixing.
You are right. I don't think the Madrid dressing room is in a bad state either. A few weeks ago we heard rumors that Vinicius junior wanted a pay rise. And we saw rumors that he had demanded a large sum of money. Madrid management probably didn't accept all of Vini's conditions. But we don't see that Vini is not happy with Madrid.
This season we can see the bond between Vini and Mbappe getting stronger. Last season we saw some unfriendly behavior between Vini, but this season we don't see that. The bond between Vini and Mbappe is better than before and it is visible.
If Alonso can fix the weaknesses in Madrid's midfield, we will see consistent good performances from this team. Midfield and defense are still the biggest problems for Real Madrid