Since approx 5:30 UTC we are receiving only this response for this api call
https://www.googleapis.com/appsmarket/v2/customerLicense/{appId}/{customer}
{"error":{"errors":[{"domain":"global","reason":"forbidden","message":"Not authorized to access the application ID"}],"code":403,"message":"Not authorized to access the application ID"}}
but there has not been any previous development or changes on our side and this affects all of our marketplace applications.
Any ideas what is going on and how to fix/workaround this issue?
This issue should now be fixed by Google.
If you are still experiencing 403 Forbidden on marketplace API calls make sure you are following these guidelines
Access to these APIs is restricted: only project members of the Developer Console project associated with your application may use the API. Specifically, these project members must be in Can Edit or Is Owner roles. You may also access UserLicense and CustomerLicense as the logged in user to your app. Refer to https://cloud.google.com/compute/docs/access/add-remove-change-permissions-for-team-members to learn how to add members to your project.
For example by doing the API requests using a service account in the Google Cloud Platform Project for you application without using any impersonation/delegation.