Curious how this works. Google surely verifies things like business addresses, DUNS numbers, company principals (CEO et al), etc, eh? So what if the card is "private" if the rest is legit?

That is a good question. Maybe verification of the above data is "weak" so Brex privacy feature wins.

I do not how Google fraud system works but I know that Brex privacy feature is signal which is not good (from my experience in our company).

Sidenote: I also noticed that PayPal doe not like Brex privacy CC for subscriptions.