Mozilla released Firefox Preview 4.0 on March 9, 2020, the latest stable version of the upcoming re-interpretation of Firefox for Android. The new browser version is only available on the project’s GitHub webpage at the time of writing and not on Google Play.
One of the main new features of Firefox Preview 4.0 is initial support for browser extensions. While officially limited to the content blocker uBlock Origin, Mozilla promised that it would improve support throughout 2020 to integrate full extensions support in the new mobile Firefox browser.
The uBlock Origin extension is not enabled by default but Firefox Preview users may enable it by selecting Menu > Add-Ons Manager > uBlock Origin.
origin - https://www.pipiscrew.com/?p=17422 firefox-preview-v4-0-stable-brings-ublock-support