When the styleguide plugin was moved into core, the .discourse-compatibility file was deleted from the repository, effectively removing the plugin on all installations, including those on stable that do not incorporate the plugin.
I think it might be a good idea to restore that file
Yes given how close we are to the release you should try to make it work on your own hosting with a patch. Also I donβt expect many people to use styleguide, this was a very very niche plugin prior to it being added to core.
This was not about getting it to work on our own hosting (we already keep a repository of forks of all plugins for the stable branch), I was just reporting this because I still managed to bump my head and was trying to prevent others in encountering the same.