Mozilla acknowledged an issue affecting Firefox users after updating to the latest 70.0 release. The issue prevents websites or page elements that use dynamic JavaScript from loading. The problem is known to impact a wide range of websites including YouTube or Facebook from loading properly. Mozilla provides a temporary workaround for Firefox 70 not properly loading websites and page elements until a fix will be issued with a future release. This is the second time Firefox users experienced issues in October, seeing that Mozilla updated the Firefox 69.0.2 changelog with a note in early October saying downloading files may not work for Windows 10 users who have the Parental Controls feature toggled on.
Source: https://www.bleepingcomputer.com/news/software/mozilla-provides-workaround-for-firefox-70-not-loading-sites/