A change like this also wasn’t announced, so it comes as quite a surprise to me. From the thread announcing the added scope requirement:
Note that
chat_moderator_actionswas not formally documented other than within this discussion, however, it will require a new scope as indicated above. This topic should be considered officially supported.
That doesn’t show any indiciation that it is being changed (apart from the now required scope), since it refers to the topic as it was discussed before. It certainly doesn’t mention it being restricted to the broadcaster. It by the way also doesn’t mention who the token has to be from on the PubSub documentation.