It was an important win to take for Valencia above all else. Because they were quite close to the relegation field and they needed to find a way to get away from there. Real Madrid didn't have any big target to achieve in the league so I'm not very surprised with this result. But of course one can say that Real Madrid could still have won this match while they were controlling the ball mostly. But having a big percentage of ball possession isn't always enough to win a match in football. This was a solid example for that.
Besides we watched two different halves as well. In the first half despite the ball possession rates Valencia had many more goal attempts and this helped them score. Real Madrid took full control in the match in the second half but it didn't change anything. This wa a horrible match for especially Vinicius Junior and that red card was a bad ending.
Real Madrid thinks Valencia can't beat them, but as the game progresses, they are shocked by one goal, which they are unable to recover from until the end of the game. When they come back for the second half, they try to participate more than before, but nothing happens. Vini Jr's card makes the game worse and uncomfortable, and while I know that no one is perfect, the referee shouldn't give many cards in the match.
The next time, Real Madrid should exercise caution and refrain from playing against teams that they are unable to overcome because some of these squads pose a serious threat to other teams, especially when they face well-known teams.