Is there a best/correct practice for implementing object-level validation and the ensuing validation errors?

Django REST framework documentation suggests doing object-level validation inSerializer.validate()[1].

To do any other validation that requires access to multiple fields, add a method called.validate() to yourSerializer subclass. This method takes a single argument, which is a dictionary of field values. It should raise aserializers.ValidationError if necessary, or just return the validated values.

So if I wanted to evaluate two fields and validate that only one of these fields is given data, I might implement my serializer something like this:

fromrest_framework_json_apiimportserializersclassProductSerializer(serializers.ModelSerializer):defvalidate(self,data):ifdata.get("best_before_date")anddata.get("expiry_date"):raiseserializers.ValidationError("Specify either a best before date or an expiry date."            )returndata

However, using this serializer with django-rest-framework-json-api results in an error response that seems incorrect.

{"errors": [        {"detail":"Specify either a best before date or an expiry date.","status":"400","source": {"pointer":"/data/attributes/non_field_errors"            },"code":"invalid"        }    ]}

As far as I've understood, JSON:API error objects should have the source.pointer value as"/data/attributes/<attribute>" when an error is caused by a specific attribute, and"/data" in other cases[2].

I thought about raising this as a bug report initially, but I'm not sure if this is actually a bug or if I'm just approaching this issue incorrectly. I also madea complete minimal example with unit tests of how I've implemented this.

[1]https://www.django-rest-framework.org/api-guide/serializers/#object-level-validation
[2]https://jsonapi.org/format/#error-objects