I don't know where that information is saved, but it isn't transmitted with the normal vault format on login (at least on the website). When opening the history

I don't know where that information is saved, but it isn't transmitted with the normal vault format on login (at least on the website). When opening the history dialog for a given password/account, a new request is made specifically for the password history. The response contains the edit times in plaintext and the encrypted passwords.