google cloud error { Error: Connection refused: Bad username or password, code 5}

[ajmalvb77]

I am trying google cloud iot core connection from a raspberry in which balena os is installed , i am trying this example https://github.com/balena-io-examples/google-iot , it was working when we erase and reinstall the os inside the raspberry pi , but after running successfully for 2 to 3 days it was going to this error
this is an other error comes alternately with the previous one
MQTT error { Error: Connection refused: Bad username or password
01.12.21 16:51:37 (+0530) main at MqttClient._handleConnack (/app/node_modules/mqtt/lib/client.js:1076:15)
01.12.21 16:51:37 (+0530) main at MqttClient._handlePacket (/app/node_modules/mqtt/lib/client.js:365:12)
01.12.21 16:51:37 (+0530) main at work (/app/node_modules/mqtt/lib/client.js:283:12)
01.12.21 16:51:37 (+0530) main at Writable.writable._write (/app/node_modules/mqtt/lib/client.js:294:5)
01.12.21 16:51:37 (+0530) main at doWrite (/app/node_modules/readable-stream/lib/_stream_writable.js:428:64)
01.12.21 16:51:37 (+0530) main at writeOrBuffer (/app/node_modules/readable-stream/lib/_stream_writable.js:417:5)
01.12.21 16:51:37 (+0530) main at Writable.write (/app/node_modules/readable-stream/lib/_stream_writable.js:334:11)
01.12.21 16:51:37 (+0530) main at TLSSocket.ondata (_stream_readable.js:705:22)
01.12.21 16:51:37 (+0530) main at TLSSocket.emit (events.js:193:13)
01.12.21 16:51:37 (+0530) main at addChunk (_stream_readable.js:295:12) code: 4 }