Boruto's disrespect towards the village's traditions could also make Naruto angry. The village has a long history and set of values that Naruto holds dear. If Boruto were to openly disregard them, say by skipping important village ceremonies or not showing proper respect to the elders, Naruto would be furious as he sees himself as a protector of the village's legacy.
Another aspect could be Boruto's relationship with Sasuke. In some fanfictions, if Boruto were to develop a relationship with Sasuke that Naruto didn't approve of, like if they were to train in a way that Naruto thought was too dangerous or if Boruto started to idolize Sasuke too much and neglect his own father's teachings, Naruto would be angry.
One reason could be Boruto's recklessness. In fanfiction, Boruto might engage in dangerous stunts or actions that go against Naruto's teachings. For example, if Boruto were to use a forbidden jutsu without fully understanding the consequences, Naruto would be angry as it not only endangers Boruto but also those around him.
It could be that the fanfiction simply doesn't meet Boruto's standards for what the Naruto universe should be like. He has grown up in that world and has his own ideas about how things should be. Fanfiction can be very hit - or - miss in terms of quality and faithfulness to the source material. If it's of poor quality or changes things too much, Boruto might hate it.
It could also be due to a rift in their relationship over Boruto's ninja path. If Boruto decides to take a very different and unorthodox approach to being a ninja that Naruto doesn't approve of, such as using forbidden jutsu without proper understanding, Naruto might disown him in the fanfiction.
Perhaps Boruto disrespects the ninja way that Naruto holds so dear. In fanfiction, Boruto could be shown as being too rebellious, and Naruto, as a firm believer in the ninja values, would snap at him to correct his behavior. For example, if Boruto were to shirk his training or mock the importance of teamwork, which are fundamental to Naruto's view of being a ninja.
Maybe it's the high expectations that Naruto has for Boruto. Naruto is a hero, and he might unknowingly put a lot of pressure on Boruto to follow in his footsteps. Boruto could be scared of not being able to meet those expectations.
One possible reason could be that Tsunade makes a decision regarding the village that Naruto strongly disagrees with. For example, if she refuses to send help to a neighboring village in need, Naruto, with his strong sense of justice, might get angry. He's always been about protecting and helping others.
One possible reason could be misrepresentation of her character. In some fanfictions, authors might change her personality to fit a certain plot, like making her overly jealous or mean, which would be out of character for the gentle Hinata. This could make her seem unlikable and thus anger fans who love the original Hinata.
In the fanfiction, it could be that Kakashi is being too hard on Naruto during training. He might be pushing him beyond his limits without proper explanation or support, causing Naruto to feel frustrated and angry. Naruto is a determined character, but everyone has their breaking point.
Another reason could be if someone were to slander or disrespect his late mentor, like Iruka or Jiraiya. Naruto holds these people in high regard, and any negative remarks or actions towards them would likely enrage him.
He could be curious about how other fans perceive the events in Naruto Shippuden. Fanfictions can offer unique interpretations and perspectives that might give him new insights.
Another reason could be related to school work. If there are new rules in Hogwarts that she deems unfair regarding academics, like restrictions on library access or new grading systems that don't reward hard work properly. Hermione is all about learning and fairness in education, so this could really make her angry.