In the name of security the change way too many moving parts lately to push their hidden agenda.
Using HTTP in local LAN is fine. Using HTTP for non login-pages is fine. Using "basic authentification" (user:pwd@IP) is fine for certain use cases. Stop breaking things.
I am not using a Firefox anymore, they went insane lately, they don't bother about their community anymore. I am worried about Chrome too, TLS only for HTTP/2 is the wrong signal. So many times I couldn't open a HTTPS sites because the browser thinks the cert is broken - it was just a trivial page were I just want to read some text (not input anything) - just some me the page - something that wouldn't be a problem with HTTP.
If Firefox, Chrome or whoever want to destroy access to 1994-2017 websites, go to hell. Name your forked off thing TheMicrosoftNetwork (or what not) and see it tank rather quickly.
Huh, that's just security theater. The phisher could set up a website that does require authentication, thereby avoiding the warning.
The sensible thing to do would be to display the warning if the username contains unescaped dots. (I.e., http://cnn.com:article123456@fakenews.example.com/ would provoke warnings, but http://cnn%2Ecom:article123456@fakenews.example.com/ would not.)
http://news.ycombinator.com@1572395042 Chrome takes me to 93.184.216.34 no warning
Then I tried http://security.wellsfargo.com@customerLoginv=ar3351RandomDa...
Which stretches way past my laptops viewable URL bar... and it takes me right to badsite.null (or a valid site like example.com). If you need HTTPs you can redirect on badsite.null's web server. Very wild.