Discourse have backup tokens, which are to be used if you lose your OTP device.
You can also register the OTP in multiple devices.
FIDO2 keys can also be used, and Discourse support using multiples, so you can have backup keys stored in safe places, your main one, and the ones who are backed into your device, like Android fingerprint and Windows Laptop Hello devices.
If you did neither, you will have to contact the admin team and ask then to disable 2FA on your account.