Funny thing at work, I was handling some legacy users - we need to make sure that on the next login, if they have a weak password, they have to change it.
So the whole day I’m typing “123” as a password, 123 123 123 123 all good. So finally I’m done and now I’m testing it, and accidentally I type 1234 instead of just 123. Doesn’t really matter, either is “weak”, so I just click “Login”.
Then goes Chrome, “1234 is known as a weak password, found in breaches, you should change it”.
So TIL 123 is still good.
You would have the plaintext password at login time based on the users input. I’m guessing that’s why it happens at login time rather than proactively asking people to update their passwords.