some change on keychain in ios 15 beta

We found that the error code of the keychain was different in ios 14 and ios 15. When the bio-information registered by the user is changed, if secItemCopyMatching is called, erSecItemNotFound is received in ios 14, but erSecAuthFailed is received in ios 15. In this case, iOS 15 cannot distinguish whether authentication has failed or bio-information has changed. I want to know if this is a bug in os or if it will proceed like this in the future. If we continue to give this error code in the future, I hope there will be a guide on how to distinguish the two error codes from the developer's point of view.