I heard about it second hand from an engineering manager who knew some people there. Would love more info too. Context was an argument about introducing Kotlin on an Android team which, well, is no longer arguable (=

Edit: I found this: https://elixirforum.com/t/why-did-facebook-leave-erlang/2231, and this: https://m.facebook.com/notes/facebook-engineering/chat-stabi....