The injured Madrid players are David Alaba, Thibaut Courtois, and Brahim Diaz plus Carvajal today. It seems that Ancelotti will have to add several players to replace injured players in the winter. It may take a while, but Madrid must prepare it so that they can still compete in the League and Europe. He only has Lucas Vazquez in place of Carvajal. There is also news that Madrid wants Trent Alexxander-Arnold from Liverpool, he has a contract end in January next year.
Romano has confirmed Carvajal will return in October 2025. This is very bad news for Real Madrid's side.
I think that will force Madrid's coach, Ancellotti, to find a new RB in the winter window. Though he rarely buys a new player in winter, he needs a new RB now. It's time to replace Carvajal. A temporary fix in the winter transfer window won't work.
Carvajal is 33. His ACL injury will limit his performance. And i doubt he will back to the his peak performance.
Indeed Trent Alexxander-Arnold is Real Madrid main goals to be able to help them fill the void even though Lucas Vazquez has been there as stated by @Luzin but he is the only player who can fill the void and Carvajal injury is certain to take long time to recover and bringing in new players is the right decision in my opinion.
On the other hand there are several parts of Carvajal injury and this does make his injury can result in decrease in performance when he recovers later, what is clear is that the ACL injury problem will always reduce the quality of players at any time because the percentage of re-injury is still very possible to occur after recovery.