Cubarsi joined La Masia at the age of 11 and made his first-team debut five years later at 16. In an interview with UEFA TV, the Barcelona centre-back said that Barca's youth academy influenced his understanding of football and shaped some of his characteristics on the pitch.

One of those characteristics is his ability to play the ball out from the back, a quality he attributes to his development during his time in the club's academy: “I think the thing that represents me the most is my ability to play out from the back. This is something I learned at Barca's academy.”
The defender recalled that the team began training this style from a very young age, with the aim of controlling the rhythm of matches and starting attacks from defence: “From a very young age, we have always focused on controlling the rhythm of the game and building from the back. That is what truly defines my playing style.”
However, Cubarsi said his gains from La Masia were not only related to football. He believes the academy also played an important role in shaping his character, as he learned values there that he still maintains today: “It is not only about developing players here, it also teaches you to become a good person.”
In addition to training and everything related to football, the Catalan centre-back also highlighted the connections built among young players at Barca's academy and the time they spent together away from the pitch: “I think training, building friendships with everyone who lived there, helping each other, especially having dinner with friends we trained with and enjoying time together, that combination was wonderful and will stay with you forever.”

Cubarsi said he has always worked to prove in training that he is ready to play, trying to “maintain the highest intensity possible” in every session and aiming to “train as seriously as in a match”, while also paying attention to his diet and physical condition: “If you do things well every day, you can earn the coach's trust.”
Since making his first-team debut in January 2024, the defender admitted that he has changed both physically and technically: “I have more experience now, and I have gained some muscle; I am stronger now. Also, I have become more competitive. I think I have become a better player and I see many things more clearly.”
This competitive spirit is not something that appeared recently, but rather a part of his character since childhood: “From the outside, I may look like a well-behaved kid, but when I have to get angry, or when something happens that I do not like, I show my true side.”
The Barcelona defender admitted that he cannot accept losing, “whether it is in football, playing board games at home, or even playing billiards with my father. I never want to lose.”