Why doesn't filtering work in ModelViewSet in DRF?

Question

MongoDB

As I understand it, in order to be able to work with the database from REST requests, there is an excellent ModelViewSet model and it contains filter_backends and filter_fields, which describes the fields by which you can filter the request to the database.
The code is made following the example from the docs and docs , but it throws an error:
AttributeError 'QuerySet' object has no attribute 'model' on a GET request.
I could not determine what was wrong, I reviewed a bunch of examples and it works for everyone as described in the documentation. There was an idea that perhaps the problem is in some imports. Since I'm working with mongoengine , some imports are changed from rest_framework to rest_framework_mongoengine. But I saw examples with these imports, where supposedly everything works. What's the matter?
The code itself:
1) Serializer

from rest_framework_mongoengine.serializers import DocumentSerializer
from processing.models import SomeModel


class MySerializer(DocumentSerializer):
    class Meta:
        model = SomeModel
        fields = "__all__"

2) Submission

from rest_framework_mongoengine.viewsets import ModelViewSet as MongoModelViewSet
from django_filters.rest_framework import DjangoFilterBackend

from api.v4.serializers import MySerializer
from processing.models import SomeModel


class UsersViewSet(MongoModelViewSet):

    # queryset = SomeModel.objects.all()
    serializer_class = MySerializer
    filter_backends = (DjangoFilterBackend,)
    filter_fields = ('user', 'user_code')  # все как в документации

    def get_queryset(self):
        return SomeModel.objects.all()

As I understand it, I should get a filtered response from this url:
example.com/api/products?user=ivasic&user_code=4569