This is a small private tool used only by its owner, for the owner's own mailbox. It is not offered to the public, and no one else can sign in to it.
It signs in to one Google mailbox with read-only permission (the Gmail permission described by Google as "View your email messages and settings") so that the owner's own software can check for new mail. It cannot send, change or delete mail.
The tool keeps nothing outside the owner's own computer. It does not sell, share, publish or transfer mailbox data to anyone. It does not use mailbox data for advertising, and it does not use mailbox data to train any model. Access can be revoked at any time at myaccount.google.com/permissions.
Through the support email address shown on the Google consent screen for this app.