Defeat is as normal as winning in football and this defeat will definitely make Leverkusen more mature and can make them strengthen what they already have. Talking about the DFB Pokal, Leverkusen certainly doesn't want the same mistakes to be repeated and even though their opponents will be a weak team from a lower division, they can't underestimate them in the slightest if they want to win this title.
Yes, defeat is very normal. However, what is widely discussed and makes it seem like Leverkusen is very disappointing is because they are disappointed with Leverkusen who failed to become UEFA Europa League champions from Atalanta, even though they are the favorite team.
Apart from that, the fans also seemed shocked by Leverkusen's performance in the final, it was very poor and the effort to compete and attack was very small. Even though they have a lot of ball possession, they can't avoid defeat, because they are not attacking and effective enough in executing the ball towards the goal.
And now, we are still waiting for Leverkusen's last match to determine whether the final defeat was the only one or not. And I thought, that would be the one. For, in the DFB Pokal, the chance to win is very high if they are really able to optimize every chance and attack effectively.