You may have tried veeam feature on restoring backup data from on-prem to GCP using Veeam v11a.
If you encountered an error message like "Required 'compute.firewalls.create' permission" or network permission issue, then proceed to refer below workaround.
You need to assign correct Google Compute Engine IAM User Permission.
Please refer to
Do add an additional service account permission and Cloud Build service account permission
[Click on diagram to view in large view]
a) Service account. You need to refer to VBR Console on which service account that it create when establish connection to GCP
b) Cloud Build Service Account
Go to Cloud Build to identify your service account