This is exactly one of the problems in the legacy Internet Identity experience with passkeys weāre hoping to resolve, by moving to a single dedicated domain (id.ai) these sort of multi-domain issues should no longer be an issue.
As far as Iām aware weāve resolved various issues related to passkeys but if you come across any issues, please donāt hesitate to bring them up on the forum or by contacting support (thereās a link in the id.ai footer).
Yes, since the upgrade is mostly registering a new passkey for id.ai, downgrading is only a matter of removing the id.ai passkey in the legacy Internet Identity dashboard.
Recovery phrases are now also available in id.ai, we highly recommend to set-up a recovery phrase since those do not depend on external factors e.g. a broken YubiKey, lost access to password manager, breaking change in passkey browser API, DNS issues, losing access to e.g. Google account etc.
In case you already have a recovery phrase in the legacy Internet Identity product, this is compatible with id.ai.