Obviously a lot will have changed since you posted this but I have just tested this site using the beta of Kee 3.0 and can see one issue. It’s clearly related to the icon appearing and disappearing, as well as the Matched Login Entries box moving to the top-left of the screen, although I can’t reproduce the latter now.
What I see happening is that when you focus the username field, the website hides that field and replaces it with an entirely new username field. That was a common trick used 10-20 years ago to fool primitive credential stuffing bots and malware so I’ve seen it once or twice but it’s essentially a defunct practice and I wouldn’t expect many other websites to suffer from this same issue.
In any case, this doesn’t happen on the password input so between that and the “Matched Login Entries” button on the Kee main menu, I think it shouldn’t be too hard to sign-in to this site now.