I wouldn't necessarily consider that this is actually a bug as much as it could be a vector for others to determine if accounts exist for a particular email address.
Steps to reproduce:
Attempt to log using various combinations of correct / incorrect email addresses and passwords. By "correct email addresses", I'm referring to email addresses which have been registered for Kagi.
The front-end's response is consistent by either always blanking both credential inputs or by only blanking the password.
Currently, if I input my email address (for which I have a Kagi account; let's call it "firstname.lastname@example.org"), but use the wrong password, the password is blanked but the email address isn't. On the other hand, if I input a version of my email address which hasn't been registered (email@example.com, for example), both fields are blank.
Browser: Google Chrome, Version 101.0.4951.64 (Official Build) (64-bit)
OS: Ubuntu 22.04
Active Kagi region setting: N/A, login screen
What Kagi server you connect to: N/A, login screen