I am currently on Nextcloud 32.0.5 installed on Ubuntu 24.04 LTS.
I have TOTP, Email, and app 2fa configured and enforced.
I have generated backup codes, and the system must know this as it tells me if I generate new backup codes it will invalidate the old ones.
But I keep getting emails every couple of months (just a guess on frequency) telling me that I have not generated backup codes.