I don't know what you're talking about. Here's what I see [1], I actually like highlighting on main domain. If they'll remove https:// from my URL box, I'll grab a pitchfork myself, but for now I see no signs of it happening.

[1]: https://tinyurl.com/umluadw

The patch was pushed 18 hours ago: https://hg.mozilla.org/mozilla-central/rev/5b1cfd31cdb7

That patch seems to remove the option of striping the http(s) from the url bar. That is, you always get the http(s) and there's no option not to view that anymore.

Am I missing something?

Yes. Scroll down to the code change in UrlbarResult.jsm.

The option to control stripping was removed, and the code, rather than checking that option, /always/ strips.

Is that only in Nightly? My Firefox 75 shows the https and the full URL, and I havent changed any about:config settings.

My Nightly 77 shows the full URL and https and I also haven't changed about:config settings.

That's a temporary entry so, of course, it would be removed eventually.