Consent
GAMDaemon needs consents at two stages to make the app work.
Google account
Creates a Google profile linked account on GAMDaemon. Your Google account profile data is used to populate GAMDaemon profile too.
When a user logs in through Google SSO and grants consent, Google issues an authorization code to the application (GAMDaemon in this example). This code is a short-lived token that can be exchanged for an access token and, optionally, an ID token. This exchange is necessary because the authorization code by itself doesn’t grant access to the user’s information — it must be exchanged for tokens that do.
Google Ad Manager
Uses your Google account linked to GAM to access the data and perform operations, thereby removing need for any GService API account.
All Google Ad Manager API calls must be authorized through OAuth2 an open standard that allows users to grant permissions to third-party applications, so the application can interact with web services on the user's behalf. OAuth2 enables your Ad Manager API client application to access a user's Ad Manager account without having to handle or store the user's username or password.
To review and remove any Google account linked permissions related to 3rd party apps, visit https://myaccount.google.com/connections?pli=1
Reference:
https://developers.google.com/ad-manager/api/authentication
https://github.com/googleads/googleads-java-lib