New Gmail is dangerous and TestFlight is not helpful. – TestFlight Review

Used TestFlight to install the Beta Gmail and the Beta started to re-download previously read and deleted mail from the linked account where it showed up in my iPhone email app. No way to unlink. Had to delete the Beta app and reinstall the normal Gmail app. No way to provide feedback from TestFlight, it only allowed me to reinstall the Beta.
Review by HMarko on TestFlight.