It’s just very unfortunate timing. Google removed some library Firefox depended on in NDK and it meant developers need to make significant changes to their packaging system. At the same time critical vulnerably was discovered in Firefox. On top of that, everything happened when main developer of Fennec was away from home and short on time. But from what I’ve seen on Fennec gitlab most of the work is done so you should expect update soon.
I love the fact that summery is longer than original message.