Real Madrid currently have 6 injured players that are their main players.
-Militao
-Alaba
-Carvajal
-Tchouaméni
-Camavinga
-Vinicius
These are important players so Real Madrid's performance has declined so it is natural that they often experience defeat and Mbappe is not entirely to blame, but he always fails to convert opportunities into goals, especially Mbappe's ego is still there where he always dribbles without seeing players who are in the right position to pass the ball.
But sorry, Real Madrid has a good plan in regenerating the squad, in fact Real Madrid also still has many young players with great potential in the squad. Not only that, even some senior players are still in the Real Madrid squad and thus, even if Real Madrid the player you mentioned is injured but I still think Real Madrid is still fine. Last season, Belingham made a huge contribution to Real Madrid's success in winning the trophy but this season, after suffering an injury, it seems that Bellingham has also decreased. So, in the not-so-good results for Real Madrid so far, I don't think it's because of Mbappe but yes, because it seems like the other key players that Real Madrid have also experienced a decline in performance this season.