I found how to do what I needed... Note: when doing this, you'll lose any settings, history, bookmarks etc that are stored locally. If this is a problem, make sure to sync to a Firefox account first. 1. Uninstall Firefox in the Play Store 2. Get the v68 APK from: https://download.mozilla.org/?product=fennec-latest&os=android&lang=multi (found via https://wiki.mozilla.org/Mobile/Platforms/Android). If this link is updated to point to v79, the last release of v68 should still be available from: [removed random third-party site] https://archive.mozilla.org/pub/mobile/releases/68.11.0/ (If you use that, you need to select the right one of the 4 variants for your device. For most modern phones it'll be arm64). Worth saving the APK file somewhere safe in case you accidentally re-upgrade and need it again. 3. Install the APK, and you'll get v68 back. 4. Ensure you have auto-updating turned off in Play Store, and make sure that until we have a satisfactory latest version of Firefox, you don't accidentally "upgrade" again!