> This still leaks that the account exists and has TOTP enabled tho. You could mitigate that by prompting for an OTP code on a random but stable subset of none

> This still leaks that the account exists and has TOTP enabled tho. You could mitigate that by prompting for an OTP code on a random but stable subset of nonexistent accounts -- for example, by hashing the provided username with a server-side secret and requesting an OTP if the hash starts with a zero.