Comment by efrowning

How would the clients tell if the account has a valid sub change or not if the only piece of information provided is that the sub claim changes? For this particular attack, without having some kind of Google Workspace account identifier for the domain, the sub claim doesn't sound sufficient to validate that it's the same Google account from the client's side. I'm guessing the engineer at the major tech company didn't provide that stat without checking if those users were valid, active accounts.