If not for the arrival of Mbappe, Vinicius was the best player in Real Madrid that you can count on whenever Madrid needs a win in any match. You should see how important and good he is at his to the extent that Ancelotti have to convert Mbappe into a central forward instead, of allowing Mbappe play to play on Vini's wing. Vini will not be sold because the club needs him more than the Arab men.
Vini is no doubt an important player for Real Madrid in both Ancelotti and this present Xabi Alonso's era if he wasn't Xabi would've tried to offload him just like he's doing with Rodrygo currently but he has a major role to play for Xabi Alonso when the season start that's why he's untouchable. Real Madrid is yet to bounce back hopefully we'll see a different Madrid when the new season starts, but right now Xabi has lots of work to do in the preseason by drilling his players to improve better and give their best ahead of the new season he also has to use this period to know the suitable positions that would suit soke players and help them do better.
The real problem for Real Madrid is their midfield woes. As we saw last year, Kroos' absence significantly impacted Real Madrid. To avoid a similar problem this year, I believe they need to make a transfer in this area. Vinicius, Mbappé, Rodrygo, and Bellingham are all effective attacking players for this team. However, they lack a master of control in midfield. A transfer in that area would raise the team's level. However, they probably haven't figured out who to bring in for this position. I'm sure manager Xabi Alonso has a plan.
I don't understand how you see the problem in Real Madrid's midfield. You might be thinking that Madrid's midfield used to have Toni Kroos and Luka Modrić and Real Madrid released these two players and that's why you think Real Madrid's midfield is weak, if you think like that then I would say you are wrong. Real Madrid released Luka Modrić and Toni Kroos because they already have several capable midfielders in the club like Jude Bellingham and Federico Valverde. If you talk about Real Madrid's problems then you definitely have to talk about Real Madrid's defense position. Real Madrid finished the last season with a bad experience in defense. The main reason for such a bad defense is the injuries of regular players. When Real Madrid takes the field with an injury-free XI, Real Madrid will undoubtedly be the most dangerous team among European clubs.