surely now all clubs are tidying up and preparing for next season. but it seems that currently the one who is relaxed is Barcelona because unlike other teams participating in the Club World Cup and surely Barcelona when competing later their stamina will certainly have the potential to be stronger.
I am sure that a long break will not be comfortable enough for players who are used to playing with short breaks. By playing, they actually maintain their fitness. With a long break, players should do their own training to keep their stamina up.
And actually, something that is an advantage for teams participating in the Club World Cup. Especially those who have new coaches or new players who can be played. So each team can prepare for the tighter competition next season.
Yes, if we look at it from this perspective, maybe you are right. Because the players are playing matches again without getting enough rest and they are catching up with form. Especially Real Madrid needs to play with each other a lot. Because the team is trying to adapt to each other with the new coach. The best way to do this is to play matches frequently. Real Madrid is doing very well right now, but I don't know if they can continue it.