I have recently added the BBCode plugin to our (self-hosted) Discourse instance. Today I checked the plugin list in the admin area and noticed that the footnote and spoiler alert plugins seem to have added automatically as a consequence of that.
However, my understanding was that both plugins have moved into Discourse core, so I was wondering if this is maybe a left-over dependency of the BBCode plugin that should have been removed or if it simply causes these parts of core to surface.
For the record: both do not show as part of the update screen.
Discourse chat was also merged with core and still shows in your plugin list. As Jay said this is normal.
Chat being merged messed me up as I had missed the announcement stating it was bundled with core and tried to install it. Not recommended but was easy fix as just removed it from my app.yml as the 2nd install caused site not to rebuild.
Ok, thanks! Then everything should be fine. I was just slightly worried that an outdated dependency might have caused the installation of plugin versions that are potentially older than what it is integrated in core.