Simply put, Vinicius has started playing as a midfielder to allow, as you say, Mbappe to score more goals, who apparently seems to be increasingly playing as the first lady within the team, and that doesn't surprise me given that he did the same thing at Paris Saint-Germain.
It's a forward partnership that their coach has designed, and Vinicius can also score directly when he has the opportunity and can't pass to Mbappé. This means that both players play up front, although their positions are slightly different, but not so far apart that Mbappé has more to learn in terms of finishing when a pass comes to him in every game. And for next season, I'd prefer Real Madrid players who can work together well to improve the team's strength, because last season Real Madrid really couldn't do much in any competition.