Thank you :)
No access to extensions and blocking about:config was to me just heretic. Those two are the raison d'être of Firefox.
Nightly build thankfully reverted this babysitting of users but indeed we are still stuck with 'vetted' add-ons downgrade in the official Firefox release for Android.
Also lots of other little papercuts: https://news.ycombinator.com/item?id=26470454