It could be related to the casualties during the war. Maybe some families of the fallen blame Naruto for not being able to save their loved ones. They could put pressure on the village leaders to banish him. And also, the new generation of shinobi might see Naruto as an obstacle to their own rise to power. They might convince the elders to banish him so that they can have more opportunities to shine.
Perhaps it's due to jealousy. Naruto has become a hero, and some people in power might be jealous of his popularity. They could spread false rumors or use some pretext to banish him. It could also be that the village wants to distance itself from Naruto to avoid being a target of future attacks. Since he's so well - known, enemies might target the village just to get to him.
One possible reason could be political. After the war, the villages might be restructuring and Naruto, with his great power, could be seen as a threat. Another reason might be related to the secrets he knows. Maybe some powerful figures don't want him to expose certain things. Also, his Jinchuuriki status could play a role. People might still be fearful of the power within him even after the war.
In fanfiction, it could be due to a prophecy. Suppose there was a prophecy that Naruto would bring great danger to the village in the future. Tsunade, despite her bond with Naruto, might believe in the prophecy and banish him to prevent the foreseen disaster. Also, it could be related to Naruto's power. If his power was growing too rapidly and becoming uncontrollable, Tsunade might banish him to protect the village from any potential harm his power could cause.
One possible reason could be political pressure. Maybe some powerful clans in the village see Naruto as a threat due to his growing power and influence. They might force Tsunade's hand to banish him to maintain their own status quo in the village.
Perhaps Naruto was falsely accused of something really serious in the fanfiction. Like he was thought to be involved with the enemy in some way. Kushina, being in a position of power, had to banish him to maintain the order and trust within the village, even if she didn't truly believe he was guilty.
One possible reason could be fear. The villagers have always feared the Nine - Tails within Naruto. His family might banish him out of this same fear, not wanting to be associated with the potential danger he represents. Maybe they think that by banishing him, they can keep the village safe from the Nine - Tails' power getting out of control.
One possible reason could be fear. If Naruto became so powerful that he was like a god after the war, the other villages might fear his strength and influence. They could pressure the Hidden Leaf to banish him to safeguard their own interests. Another reason might be internal politics within the Hidden Leaf. Some power - hungry individuals or groups might see Naruto as a threat to their authority and use the post - war situation to get rid of him.
One possible reason could be for Naruto's protection. Maybe she thought by banishing him from a certain place or situation, she could keep him away from a hidden danger that she knew about. For example, there might be a powerful enemy targeting Naruto specifically, and she believed that by making him leave, he would be harder to find.
Maybe in the fanfiction, Naruto has discovered a new family or group of friends outside the village who are in need of his help more urgently. He has to prioritize them over the village that banished him. He could also be trying to teach the village a lesson about the consequences of their actions by refusing to help.
One possible reason could be fear. Naruto's 'godlike' powers might be too much for the village to handle. They could be afraid that he might accidentally cause destruction. Another reason might be envy among some of the villagers or ninja. They may not like that Naruto has become so powerful all of a sudden and want him out of the way.
Well, perhaps in the fanfiction world, Naruto's parents discover some kind of 'dark power' within him that they fear might be uncontrollable. They think that banishing him is the only way to keep the village safe from this potential threat. This could be a power that is different from the Nine - Tails' chakra and seems extremely dangerous to them.
One possible reason could be false accusations of a serious crime. For example, if he was wrongly blamed for a major attack on the village. Another reason might be political intrigue. Some powerful figures in the village might see Naruto as a threat to their power and find a way to banish him to maintain their control.