Updating Email in Firebase Auth still allows sign in from previous Email.

I was building a feature of Account Transfer from 1 email to another. For that, I updated the UserEmail field for the specific UID using the GO SDK. The new Email got updated but when I tried logging in from the previous Email, it was still able to login but the email which I got was the changed one. Even when searching via email from the Firebase Console in Auth section. I was able to query the new updated email from the last email. Is there a way to prevent this behaviour.