I still think Real Madrid is quite serious in building their team this season because their less than optimal performance lately does not mean that they should judge them as not serious in playing in every match. But it is more about the performance of their players who are a bit chaotic because there are old players who have retired and also there are new players who may not be used to the tactics in Real Madrid. So I will not judge them for seriousness or not because in reality they are really serious in every match even though the results may look different for this season.
Madrid only brought in two players this season, namely Mbappe and Endrick, so adaptation should not be the reason for Madrid slump, especially since the league has entered week 13, what does it take that long for a star player to adapt to the game of his new team?
Meanwhile, the retirement of kroos and the absence of players who can cover the hole left by kroos in the midfield in my opinion is a slightly better reason than players adapt.
Mbappe was a huge part of the teams efforts for years, so he is definitely an adaptation issue. They got him to play at striker, and he is not a striker at all, he is a left wing, and Real Madrid has one of the most established left wingers of all time right now, it's guaranteed that they are not going to move Vinicious Jr. to any other place, and Mbappe wants to play there for some reason. He is making a bigger deal it should be, he is asking to get that kind of replacement and because of that I am not entirely sure if we are going to see this growing to be a bigger problem at all.
I am not sure if we are going to see them making a bigger change or not, but this isn't normal and we shouldn't really be seeing them playing worse after adding a great player like him. Ancelotti has to pull off some magic and convince Mbappe that he would be better at striker to make sure that team doesn't get interrupted like this, or they will keep on being worse.