According to BigQuery (BQ) API documentation, streaming insert (insertAll) input should be formed as
{"rows": [ {"insertId": "A String",
"json": {"a_key": ""},
},
],
}

(see https://developers.google.com/resources/api-libraries/documentation/bigquery/v2/python/latest/bigquery_v2.tabledata.html)

whereas in the example bigquery/api/streaming.py the input is formed differently as

insert_all_data = {
'insertId': str(uuid.uuid4()),
'rows': [{'json': row}]
}

The difference is where you place the 'insertId' key. A separate insertId should be with each row, not one 'insertId' at the same level with 'rows'