The fix given for issue https://issues.redhat.com/browse/OCPBUGS-42014(pointing to same problem) was at service account key creation. but the actual problem lies at service account creation itself.  

We suggest upgrading terraform and provider to the latest version in openshift-installer for 4.12+. The underlying issue is already fixed upstream and released in v6.45.0.

Note: we see this problem more often in lower openshift versions 4.12, 4.13 than in 4.16.

Intermittent

    1.Install the UPI openshift cluster in GCP platform
    2.
    3.
    

    level=error msg=Error: Provider produced inconsistent result after apply
level=error
level=error msg=When applying changes to
level=error msg=module.master.google_service_account.master-node-sa[0], provider
level=error msg="provider[\"openshift/local/google\"]" produced an unexpected new value: Root
level=error msg=resource was present, but now absent.
level=error
level=error msg=This is a bug in the provider, which should be reported in the provider's own