Version 2 of Firefox’s SmartBlock feature further improves private browsing. Third-party Facebook scripts are blocked to prevent you from being tracked, but are now automatically loaded “just in time” if you decide to “Log in with Facebook” on any website.
Support for Private Fields (TC39 proposal, stage 3) is available in DevTools. The support includes: object inspection, autocompletion, expression evaluation, variable tooltips, and pretty printing (bug)
The Network panel shows a preview of HTTP requests for fonts in the Response tab (bug)
Support for Fetch Metadata Request Headers, which allows web applications to better protect themselves and their users against various cross-origin threats.
Added the ability to use client authentication certificates stored in hardware tokens or in Operating System storage.
Printing a page with scaling may result in truncated output (bug 1720621)