Get_next_by_FOO method incorrectly returns link

My problem is that I specify the get_next_by_FOO method, but the link does not work correctly.

#models.py

class Project(models.Model):
    user = ForeignKey(settings.AUTH_USER_MODEL, on_delete=CASCADE, db_index=True)
    name = CharField(max_length=150, db_index=True)
    cover = models.ImageField( upload_to="project_photos/", null=True, blank=True
    )
    site = URLField( max_length=200)
    description = TextField()
    note = CharField( max_length=150)
    created_at = DateTimeField(auto_now_add=True)


    def next(self):
        return self.get_next_by_created_at()

    def pre(self):
        return self.get_previous_by_created_at()

#html

<a href="">Next project</a>
<a href="">Previous project</a>

And it gives out the following link:

http://localhost:8000/projects/8/%D0%9D%D0%BE%D0%B2%D0%B0%D1%8F%20%D1%80%D1%83%D0%B1%D1%80%D0%B8%D0%BA%D0%B0

The id of the model does not change, and the name of the next or previous model instance is appended to the end of the link