Board Thread:Support Requests - Getting Started/@comment-45171933-20200309021537/@comment-9605025-20200309201040

They aren't announced or anything. It is just Fandom occasionally runs sweeps to remove small inactive wikis so that they don't clutter the servers and hog resources for no reason. The fact that you have started editing the old wiki should be enough to protect it from such a sweep. Usually a wiki must be both inactive and very small in order to be deleted by a sweep. Wikis that are small but active as well as wikis that are inactive but "large" are usually left alone. Of course, "large" is a subjective term.