How to Downgrade Firefox on Android
Firefox recently updated their Android App to version 80, which took away a lot of functionalities - such as removing the about:config, data saver, extensions or add-ons, easy access to bookmarks, etc.
A lot of longtime Firefox fans are upset naturally... but instead of straight up uninstalling the app, I'm going to show you how to revert it back to a previous version that worked for you. You can use this method to revert any app on android.
Instructions:
1. Uninstall Firefox (settings: apps: firefox: uninstall)
2. Disable auto-update on Google Play (settings: auto-update)
3. Search for "old Firefox android" or "old firefox apk" using Chrome or any browser on your phone
4. Allow installation from Chrome if Android asks for permission
I'm currently running an old Firefox 79.0.4 version and it's good to have the old version back.