[Fixed]-Filtering nested resources Django REST Framework

You have to override the get_queryset method on your viewset and filter the prefetch_related query:

def get_queryset(self):
    # get the filter value
    modelb_id = self.request.query_params.get('modelab__modelb__id', None)
    queryset_modelab = ModelAB.objects.all()
    # you can use django-filter class here too
    if modelb_id:
        queryset_modelab = queryset_modelab.filter(modelb_id=modelb_id)
    queryset_modelab.select_related('modelb')
    queryset = (ModelA.objects
                .prefetch_related(
                    Prefetch('modelab_set', queryset=queryset_modelab))
                .all())
    # modela filter class will work on this queryset
    return queryset