NodeJS Backend accessing Cloud Storage suddenly gives “Could not load the default credentials.” without any change or deployment

Solution for NodeJS Backend accessing Cloud Storage suddenly gives “Could not load the default credentials.” without any change or deployment
is Given Below:

We have a NodeJS Backend using the client library for Google Cloud Storage and we are initializing using the default credentials which is the service account we set in the cluster. That was working without any problem for the past 2 years but 2 days ago it suddenly started giving the error:

"Could not load the default credentials. Browse to https://developers.google.com/accounts/docs/application-default-credentials for more information."

We investigated what could be the cause, but we didn’t make any change in the cluster, not even a deployment.

EDIT:
The NodeJS is running in a container inside a pod that also has an ESP container inside. The service account is set in the node pool. We are not using AppEngine.

Any ideas? Anybody had a similar problem?