Three endpoints (media, metadata, and references) have recently been removed from the REST API (82565490ffe9). I have seen recent discussion around the media endpoint (T248553), and as far as I understand this decision has been made as these endpoints were resource-heavy and none of the official apps were using them (but forgive me if I didn't manage to dig up some of the discussions, I am completely new to this platform).

I have created this task to ask whether the features previously implemented by the page/metadata/ endpoint are planned to be implemented in this API at any time down the road. The two that I'm personally mainly interested in are the available languages list (which is already implemented by the Mediawiki API, and I believe that is currently used by the mobile version of Wikipedia), and the hatnotes (which I believe are not a part of the Mediawiki API as their own fuction, at least I couldn't find them, they also don't appear to be supported by the official Android app, related: T240721).

Just to explain my interest in the endpoint, I've developed https://wikitranslator.github.io, which is a Wikipedia-based translation engine. I use the REST API for article summaries (works great there!), and used to use it for the two things mentioned above. I have re-implemented the translation itself using the Mediawiki API after the endpoint closed (it was marked experimental, so the lack of notification is arguably understandable), but would appreciate any help in terms of other ways of implementing hatnotes!