Do not blame Real Madrid for not giving Kubo playing time, clubs like Real Madrid don't use most of their academy players. Real Madrid likes using already-made players, so they can be a threat to other clubs. And that is the footsteps Manchester City has taken, and they are becoming with it.
Already-made players is simply the correct odd for Real Madrid. Kubo is good but he's still young and have more years to play football, Real Madrid loaned him out for the player to start developing experience and becoming a pro player on the pitch. Real Madrid are only in for the players, they don't settle for any lesser results, the main reason they're still standing top today is simply because they're not stepping below their performance, only triggering good transfers on balance players and not some random faded players, not players that have fallen out of prime.
And we have seen more positive results from the steps or policies taken by the Real Madrid club to date. In fact, I like how Real Madrid recruits players. They are not in a hurry like other teams. Real Madrid made a good approach and then got it. And until now it is very rare for a player transfer carried out by Real Madrid to be a failure. Most of the player transfers carried out by Real Madrid are more successful transfers. Kubo is a talented young player. Not just at his current club. But I also saw this player become one of the most impressive players at last year's World Cup when he played for the Japanese national team. But Real Madrid is a club with a high level of selectivity. So Kubo also couldn't compete at that time when he was young. He was loaned out more and then released to Real Sociedad. And the young players at Real Madrid currently also have to learn and show their performance to the maximum. Or they will suffer the same fate as Kubo.