LTE and GTE filters do not work inside Viewset

I defined DjangoFilterBackend inside filter_backends and added (tried to) the correct definitions as shown in filter_fields. It does not give any error in url search but it does not give any result (as filtered) in shown URL:

http://127.0.0.1:8000/api/publicusers/?deliveredtotime__lte=50

class User(AbstractUser, PermissionsMixin):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    username = models.CharField(max_length=40, unique=True, default='undefinedusername')
    deliveredtotime = models.IntegerField(default='0')

class PublicUserViewSet(viewsets.ModelViewSet):
    permission_classes = (IsAuthenticated,)
    queryset = User.objects.all()
    serializer_class = UserSerializer
    filter_backends = [filters.SearchFilter,DjangoFilterBackend]
    pagination_class = StandardResultsSetPagination
    filter_fields = { 'deliveredtotime': ['gte', 'lte']  }

What am I doing wrong?

>Solution :

filter_fields has been renamed to filterset_fields since django-filter-22.1:

class PublicUserViewSet(viewsets.ModelViewSet):
    permission_classes = (IsAuthenticated,)
    queryset = User.objects.all()
    serializer_class = UserSerializer
    filter_backends = [filters.SearchFilter, DjangoFilterBackend]
    pagination_class = StandardResultsSetPagination
    filterset_fields = {
        'deliveredtotime': ['gte', 'lte']
    }  # 🖘 not filter_fields