It might also cause Naruto to lose control more easily. If he hears such a hurtful term from someone he cares about like Sakura, it could make him more vulnerable to the Nine - Tails' influence. In the long run, it could be a turning point in his character development, either making him more bitter or more determined to show everyone, including Sakura, that he's not what she says.
It could also lead to some division among the Naruto fandom. Those who support Sakura's view might be more critical of fanfiction, while those who love fanfiction might not like Sakura as much because of her stance. For example, in online Naruto communities, there could be debates and arguments about whether Sakura is right to hate fanfiction.
He could also get angry. After all, being misjudged like that is unfair. His anger could lead him to either lash out verbally at Sakura or he could leave the village in a fit of rage, feeling that he is not accepted even by his friends. This could then lead to a series of events where Naruto has to find his own way and Sakura realizes her mistake later on.
Well, it could be that in this fanfiction, Naruto has some sort of hidden agenda. He might call Sakura ugly as a form of reverse psychology. He could be thinking that by doing so, she'll prove him wrong and become more confident. Or perhaps there's some miscommunication or misunderstanding between them. For example, Naruto misheard someone talking about Sakura in a negative way regarding her looks and he wrongly believes it, so he says she's ugly.
One possible reason could be Naruto's out - of - control power. If in the fanfiction Naruto has some new and extremely powerful abilities that he can't fully manage, Sakura might see him as a monster out of fear. For example, if he accidentally causes destruction while trying to save the village.
It could create a rift within the overall story's world. Fans who love Naruto might not like this portrayal, which could lead to a divide among the fan base. Also, other characters in the story might have to take sides, either with Naruto or with the team that hates him, causing more conflict and drama within the fanfiction.
The whole team dynamic could be affected. If Sasuke is also there, he might react in a certain way. He could side with Naruto, thinking Sakura was being too much, or he could defend Sakura. This would then change the way the three of them interact for the rest of the fanfiction story.
She might be really hurt and start to question her self - worth. Maybe she becomes more withdrawn and less confident in herself.
In fanfic, when Naruto loses control, he might accidentally harm his friends. His powerful chakra could go berserk and cause destruction around him. For example, he could lose control during a battle and end up attacking his comrades instead of the enemy.
One possible consequence could be that Naruto is ostracized by some in the ninja world. Since controlling blood is a rather strange and perhaps 'creepy' ability to some, they might view him with suspicion or fear. This could lead to him having to prove himself more often in battles and interactions.
His reputation in the ninja world could be damaged. If Padme spreads false information or reveals his secrets, other ninja might view Naruto differently. They could see him as a liability or a threat. This could lead to him being isolated in the ninja community, and he might have to fight harder to prove himself again.