TypeError: Object of type function is not JSON serializable when using flask_jwt_extended int RESTful API

I'm building a REST API using flask. I'm using postman for testing a route that creates a new item in my database, but only if the user is logged in. The routes for registering and login are working well, the last one returns the token using flask_jwt_extended module. When I send a post request to my "/api/notes" (creates a new note in database) I get the error bellow:

" (...) raise TypeError(f'Object of type {o.class.name} '

TypeError: Object of type function is not JSON serializable"

for the request I'm using the authorization tab of postman. type: Bearer Token, and my token in the field (tried with and without quotation marks)

I had faced this error this morning, before implementing my one-many relantionship, but I got it working by replacing my VERY_LONG_TOKEN with "VERY_LONG_TOKEN" in the Barear token field. I thought that because the token includes dots, it was interpreting as a function. But after implementing the relationship, I went to test and got this error again.

my note.py file:

from flask import request, Response, jsonify
from app.models import User, Note
from flask_restful import Resource
from flask_jwt_extended import jwt_required, get_jwt_identity

class NotesApi(Resource):
    def get(self):
        notes = Note.objects().to_json()
        return Response(notes, mimetype="application/json", status=200)

    @jwt_required  
    def post(self):  # post method I'm making a request for
        print("fool")  # this doesn't get printed  ->  not reaching 
        user_id = get_jwt_identity()
        data = request.get_json(force=True)
        if data:
            user = User.objects(id=user_id) # logged in user
            note = Note(**data, user_author=user) # creates note with the author
            note.save()
            user.update(push__notes=note) # add this note to users notes
            user.save()
            id = str(note.id)
            return {'id': id}, 200
        else:
            return {'error': 'missing data'}, 400

my models.py:

from app import db  # using mongodb
from datetime import datetime
from flask_bcrypt import generate_password_hash, check_password_hash

class Note(db.Document):
    title = db.StringField(max_length=120,required=True)
    content = db.StringField(required=True)
    status = db.BooleanField(required=True, default=False)
    date_modified = db.DateTimeField(default=datetime.utcnow)
    user_author = db.ReferenceField('User')
    
class User(db.Document):
    username = db.StringField(max_length=100, required=True, unique=True)
    email = db.StringField(max_length=120, required=True, unique=True)
    password = db.StringField(required=True)
    remember_me = db.BooleanField(default=False)
    notes = db.ListField(db.ReferenceField('Note', reverse_delete_rule=db.PULL)) # one-many relationship

    def hash_password(self):
        self.password = generate_password_hash(self.password).decode('utf8')

    def check_password(self, password):
        return check_password_hash(self.password, password)


User.register_delete_rule(Note, 'user_author', db.CASCADE)

init.py:

from flask import Flask
from config import Config  # my config class to set MONGOBD_HOST and SECRET_CLASS
from flask_mongoengine import MongoEngine
from flask_restful import Api
from flask_bcrypt import Bcrypt
from flask_jwt_extended import JWTManager

app = Flask(__name__)
app.config.from_object(Config)
db = MongoEngine(app)
api = Api(app)
bcrypt = Bcrypt(app)
jwt = JWTManager(app)

from app.resources.routes import initialize_routes
initialize_routes(api) 

resources/routes.py:

from .note import NotesApi, NoteApi
from .auth import SignupApi, LoginApi

def initialize_routes(api):
    api.add_resource(NotesApi, '/api/notes')
    api.add_resource(NoteApi, '/api/note/<id>')
    api.add_resource(SignupApi, '/api/auth/signup')
    api.add_resource(LoginApi, '/api/auth/login')

folder structure:

app
  |_ resources
      |_ auth.py  # signup working well, login also working, return a token (type = String)
      |_ note.py
      |_ routes.py
  |_ __init__.py
  |_ models.py
config.py
appname.py  #just import app and do a app.run()

body of my post request:

{
   "title": "test0",
   "content": "test0"  
}

Did anyone faced it before or know how to solve it?

Edit: added more code info

Looks like flask-jwt-extended released a new version over the weekend. As part of the API changes, the @jwt_required decorator is now @jwt_required()

https://flask-jwt-extended.readthedocs.io/en/stable/v4_upgrade_guide.html#api-changes