Mbappe was indeed brought in to help Real Madrid's performance, especially the front line, but what is happening now is far from expectations, Mbappe can't do much but instead he is always the reason Real Madrid fails to win the match.
Since Vinicius' injury, the Real Madrid team has no other hope except Mbappe in the front line and Ancelotti has maximized Mbappe's position but he can't show his best performance.
The initial goal was indeed like that, he was brought in to complement the sharpness of the front line after Benzema was gone. However his role has actually taken Vinicius position. From the start Madrid actually made a mistake in recruiting Mbappe, because Madrid needed a striker who could fill the midfield. Now it is proven that instability occurs due to the fight for the left position that Vinicius has occupied for a long time. Are the results better? of course not
So for now I prefer Madrid formation without Mbappe.
Currently, Mbappe is the one on that position since Vini is on injury but still he is incapable of playing the role properly. I wouldn't blame Real Madrid for recruiting him because everybody was happy that Mbappe will be the best player to replace Benzema that period that he was on fire, but it's obvious that he can't.
I will say that Bellingham did better when he came to Madrid last season because it was their joint force with Vini and other players that gave them those two cups. Currently, that Vini is not around Bellingham has been helpful in scoring goals. This is the best time for Mbappe to make his name but he is not using his opportunities wisely.