Its standard otp, google authenticator works, not sure what else, but thats what I've been testing with.
I held back payouts last night as we had an extremely high number of backed up rounds to trade (almost the day's worth). I was working through some of that backlog late last night but somewhat fell asleep

I'll push a payout out this morning based on whatever we have, and the rest will just carry forward.
I'm pretty sure Microsoft Authenticator also works, tried it for other services and the generated code was equal to the google authenticator, after scanning QR. So that seems like a fine solution and explains why everyone uses it (localbitcoins, mt gox, btc-e, etc).