delete_item doesn't return empty Attributes when specifying ALL_OLD ReturnValues

[markonosetypless]

removed_item = table_resource.delete_item(
    Key={
        "PK": "PK",
        "SK": "SK",
    },
    ReturnValues="ALL_OLD",
)

if not removed_item["Attributes"]:
    pass # item did not exist

It used to be that deleting a non existing item would return an empty Attributes property in the response, but this seems to no longer be the case? When deleting a non existing item the property Attributes no longer exists in the response, when was this changed?