Password in iCloud Keychain is different..but not shown

Occasionally when I try to log into a website by manually entering a password I get a message that the wrong password I just entered is different from the password in my iCloud Keychain and asking if I would like to replace it.

The problem is that the password isn’t shown in keychain, which is why i had to manually enter it. Of course the password I’m manually entering is wrong and I cant remember what the correct one is.

So why does the Keychain seemingly know what my password is, but not show it in the keychain? I have checked both my iOS devices to see if maybe one of them had the password stored locally and this was just a sync issue, but neither have it. So it seems to be in the cloud somewhere, because iOS knows its not the one I typed into the website, but it wont show me what it is.