Yes, I found that, but that's not even an inadequate error message -- it's just wrong. Firefox has no way to tell if the connection is encrypted or not because the connection is being dropped while the encryption is being established.
But yeah I noticed this trend too in browsers, it's getting harder to get to the technical bits every time they try to make these warnings more user friendly. I usually switch to openssl s_client in a terminal at this point.
I've been aware of it since Linus Torvalds pointed out that so called "ux-improvements" were actually ux problems back in gnome 2.
UX-ers here (hopefully there must be a few ones from Google and Mozilla here): please help stop this long trend of dumbification. I'm not asking you to make it like bash and vim just to stop hiding menus, removing settings etc etc.
This is one of only HTTPS errors that you aren't required to click through to uncover the details of the error—the connection is being shut down.