As someone that doesn’t really like using nightly, noting specific features that are currently in nightly but not in stable annoys me.
privacy.trackingprotection.ui.enabled = true has been left hanging in nightly for probably over at least 2 years. Personally, when it first came out on stable for Private Browsing I was like "so… I assumed Private Browsing, by definition, was already protecting my privacy. Well, it did, but just in case someone else at my computer wanted to see what I was up to. Still didn’t cover the external threat. But now it does a little bit of external tracking protection- which, to be honest, feels lame. Disconnect.me basic list is like 30 tracking sites whereas there are thousands in existence.
privacy.resistFingerprinting has lingered in nightly for over a year and encompasses some bugs left unresolved for over 7 years.
It makes me leave feeling that some development gets stuck.