Mozilla recently released containerized tabs[0], I imagine the next logic step is building containerized Private Browsing Mode

[0]: https://addons.mozilla.org/en-US/firefox/addon/multi-account...

My understanding is that things actually went the other way. Private browsing came first, then the same approach was used to create more labels than just "private" and not "private". I think more features may be turned off in private browsing mode though.

I use multiple computers daily and not having those synced with my Firefox account is a pain in the ass.