Let's also not forget that last season at the beginning of the season they played well only towards the middle of the season and towards the end of their performance deteriorated so seeing things like this could not this also be one of the possibilities that happened.
Their mentality is good I'm aware of that but when they can't maintain consistency with a lot of schedules (like last season) then the worst possibility of last season is also repeated.
Of course, this competition does not only run in one or two games. But it will take a long time and many games will be passed. Last season there were some injury problems and the age of the Madrid players is quite old. Anceloti has realised that and they are starting to regenerate. Just look at new names like Bellingham and Guler. But the bad thing is that some of their best players are currently suffering from severe injuries and long breaks.
It could be argued that one of the reasons Real Madrid didn't perform at their best last season was because they didn't have the depth of a squad, and they often didn't play with a full squad. Benzema, as we know, was often absent due to a number of problems, and Real Madrid didn't have a player who could replace him. The age factor as you say doesn't really matter, because as we can see the senior players Real Madrid have are still playing well. The focus is on their attacking line, which always struggles when playing without players who have now left for the SPL.