Ugly modal showing up after the session expires

[Presskopp]

I went back to a WP Site after obviously the session has expired. I was facing a amsll, empty modal. After scrolling a bit down I could read "Briefly unavailable for scheduled maintenance. Check back in a minute." - see screenshots. I can't tell what I did before on that site, but anyway, this modal needs to be adjusted.

It seems to get rendered in wp_auth_check_html() while wp_maintenance() is kicking in.

[Presskopp]

amsll = small

[swissspidy]

Usually the modal looks like this:

In your case it seems the site just happened to go into maintenance mode at the same time.