TypeError 'bool' object is not callable in django

I am implementing login function using simple-jwt module in django. At this time, only users who have authenticated their e-mail can log in, and the following error occurs in this conditional sentence.

TypeError 'bool' object is not callable in django

I don't know why I can't bring in a bool type variable. How can I fix this error? Here is my code.

views.py

from .models import User
from .utils import Util
from .serializers import customRegisterSerializer, customLoginSerializer, customTokenRefreshSerializer, userProfileSerializer
from rest_framework.permissions import IsAuthenticated
from rest_framework.generics import GenericAPIView
from rest_framework_simplejwt.tokens import RefreshToken
from rest_framework_simplejwt.views import TokenObtainPairView, TokenRefreshView
from rest_framework.viewsets import ModelViewSet
from rest_framework.response import Response
from django.urls import reverse
from django.conf import settings
from django.contrib.sites.shortcuts import get_current_site
import jwt

class customSignUpView (GenericAPIView) :
    serializer_class = customRegisterSerializer

    def post (self, request) :
        user = request.data
        serializer = self.serializer_class(data=user)
        serializer.is_valid(raise_exception=True)
        serializer.save()
        user = User.objects.get(email=serializer.data['email'])

        token = RefreshToken.for_user(user).access_token

        current_site = get_current_site(request).domain
        relativeLink = reverse('emailVerify')
        
        absurls = F'http://{current_site}{relativeLink}?token={token}'
        email_body = F'Hi {user.username} Use link below to verify your email \n{absurls}'
        data = {'email_body': email_body, 'to_email': user.email, 'email_subject': 'Verify your email'}
        Util.send_email(data)
        
        return Response({'message': '이메일을 확인하세요'}, status=201)

class customLoginView (GenericAPIView) :
    serializer_class = customLoginSerializer

    def post (self, request) :
        serializer = self.serializer_class(data=request.data)
        serializer.is_valid(raise_exception=True)

        try :
            user = User.objects.get(email=serializer.data['email'])

        except User.DoesNotExist :
            return Response({'message': '아이디 또는 비밀번호를 확인해주세요.'}, status=401)

        if not user.is_verified() :
            return Response({'message': '이메일 인증을 먼저 해주세요.'}, status=401)

        token = RefreshToken.for_user(user)

        data = {
            'token_type': 'Bearer',
            'access_token': str(token.access_token),
            'expired_at': str(datetime.now() + timedelta(hours=6)),
            'refresh_token': str(token),
            'refresh_token_expires_at': str(datetime.now() + timedelta(days=30))
        }

        return Response(data, status=200)

class customRefreshView (TokenRefreshView) :
    serializer_class = customTokenRefreshSerializer

class VerifyEmail (GenericAPIView) :

    def get (self, request) :
        token = request.GET.get('token')

        try :
            payload = jwt.decode(token, settings.SECRET_KEY)
            user = User.objects.get(id=payload['user_id'])
            if not user.is_verified :
                user.is_verified = True
                user.save()
            return Response({'message': '성공적으로 인증되었습니다'})

        except jwt.ExpiredSignatureError :
            return Response({'message': '인증이 만료되었습니다'}, status=400)
        
        except jwt.exceptions.DecodeError :
            return Response({'message': '잘못된 토큰입니다'}, status=400)

class userProfileView (ModelViewSet) :
    serializer_class = userProfileSerializer
    permission_classes = [IsAuthenticated]

    def list (self, request) :
        queryset = User.objects.filter(email=self.request.user)
        serializer = userProfileSerializer(queryset, many=True)

        for i in serializer.data :
            return Response(i)

Traceback

Traceback (most recent call last):
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\django\core\handlers\exception.py", line 34, in inner
    response = get_response(request)
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\django\core\handlers\base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\django\core\handlers\base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\django\views\decorators\csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\django\views\generic\base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\rest_framework\views.py", line 505, in dispatch
    response = self.handle_exception(exc)
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\rest_framework\views.py", line 465, in handle_exception
    self.raise_uncaught_exception(exc)
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\rest_framework\views.py", line 476, in raise_uncaught_exception
    raise exc
  File "C:\Users\kurak\AppData\Local\Programs\Python\Python38-32\lib\site-packages\rest_framework\views.py", line 502, in dispatch
    response = handler(request, *args, **kwargs)
  File "D:\school\대회 및 프로젝트\CoCo\api\views.py", line 50, in post
    if not user.is_verified() :
TypeError: 'bool' object is not callable