I've seen this delay in action when logging in into an old dormant Google account. After I provided correct password (and some other details I remember vaguely

I've seen this delay in action when logging in into an old dormant Google account. After I provided correct password (and some other details I remember vaguely - probably no phone number set and some problem with using the TOTP I set up long ago), it sent an email to the linked primary email and waited for a day to give it a chance to abort before logging me in. The delay is quite a bother but it's surely better than account takeover. What I mind about the process is probably the lack of transparency - what combination of factors (MFA pieces, location, inactive time, ...) launches which process? I get that transparency might help attackers here but they're the ones to have the persistence to figure out the rules anyway. Smells like security through obscurity to me.