According to Build a Google Chat app that uses Pub/Sub | Google Workspace add-ons | Google for Developers
(and also based on our previous experience )
native chat apps had their own service-xxxx@gcp-sa-gsuiteaddons.iam.gserviceaccount.com email that appeared under the “Configuration tab” below connection settings.
Now it disappeared and it’s impossible to publish a message from the app to pub/sub. Tried talking to Google Workspace support but their robotic response is that something is wrong with my app, even though my issue is that IAM permissioning between Google Native Chat and Google Cloud topics is broken and new Google Chat applications are not able to publish to a pub/sub. btw, already created apps are working and do have correct service account email displayed.