Ordernar os usuários pela quantidade de postagens que ele cadastrou

models.py

class User(db.Model, UserMixin):

    id = db.Column(db.Integer, primary_key=True)
    nickname = db.Column(db.String(200), unique=True)
    posts = db.relationship('Post', backref='author', lazy='dynamic')

    def __repr__(self):
        return '{}'.format(self.nickname)
      

class Post(db.Model):

    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(200), index=True, unique=True)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))

    def __repr__(self):
        return '{}'.format(self.title)

routes.py

from sqlalchemy import func


@bp.route('/user', methods=['GET', 'POST'])
def user():

    users = db.session.query(User, func.count(Post.user_id)).join(User.posts).limit(15).all()

    return render_template('users.html', users=users, title=(_('Usuários Ordenados')))

https://stackoverflow.com/questions/370174/sqlalchemy-with-count-group-by-and-order-by-using-the-orm

https://stackoverflow.com/questions/5973553/sqlalchemy-ordering-by-count-on-a-many-to-many-relationship