Aggregate works in MongoDB, not Pymongo

Question

Getting the following error:

raise OperationFailure(errmsg, code, response, max_wire_version) pymongo.errors.OperationFailure: Out of memory, full error: {'operationTime': Timestamp(1650998892, 1), 'ok': 0.0, 'errmsg': 'Out of memory', 'code': 139, 'codeName': 'JSInterpreterFailure', '$clusterTime': {'clusterTime': Timestamp(1650998892, 1), 'signature': {'hash': b'Z\x93L\x033\xe6 \x82|\x82wA\xf3Bh\xe7\xae\xce\x0c\x17', 'keyId': 7031229705458024454}}}

The following query does to work in PyMongo.

    aggregate_pipeline = [
    {
        '$project': {
        'data': "$$ROOT"
        }
    },
    {
        "$project": {
        "flattenKeys": {
            "$function": {
            "body": "function flatten(dataList, keysToHandle){while(keysToHandle.length){origKeyData = keysToHandle.shift();for (const newKey of Object.keys(origKeyData.objData)){keysToHandle.push({objData:origKeyData.objData[newKey],keyData:`${origKeyData.keyData}.${newKey}`});dataList.push(`${origKeyData.keyData}.${newKey}`);}}return dataList}",
            "args": [
                [],
                [
                {
                    'objData': "$data",
                    'keyData': "data"
                }
                ]
            ],
            "lang": "js"
            }
        }
        }
    },
    {
        '$project': {
        'matchingKeys': {
            '$filter': {
            'input': "$flattenKeys",
            'as': "item",
            'cond': {
                '$regexMatch': {
                'input': "$$item",
                'regex': fields
                }
            }
            }
        }
        }
    }]
    result = collection.aggregate(aggregate_pipeline, allowDiskUse=True)
    print(list(result))