When used with the Twenty Fourteen theme, Gutenberg removes the featured tag that makes posts show up in the home page's Featured Content section. Attempts to re-add the featured tag result in new tags called featured, but with slugs such as featured-2 and featured-3, so that the posts still do not appear in Featured Content.

A workaround would appear to be to change the featured content tag name (in Customizer/Featured Content/Tag Name) to anything else and then to change it back to featured.

To Reproduce
Steps to reproduce the behavior:

1. Install WordPress 4.9.8 on development server.
2. Install and activate Twenty Fourteen theme (v2.2).
3. Create three posts, each with several tags, among which is featured.
4. The posts will now be visible in Featured Content on the Home Page.
5. Install the Gutenberg plugin.
6. In the Gutenberg editor, the featured tag will now be invisible. If each post is saved, it will lose its featured tag and status, disappearing from Featured Content.
7. If one attempts to re-add the featured tag inside the Gutenberg editor, a new tag named featured will be created with the slug featured-2, so that the post will not appear in Featured Content. Further attempts will result in featured-3, featured-4, etc.

Expected behavior
From the point of view of the Gutenberg editor, featured should just be a tag like any other. As far as I know, it's Twenty Fourteen that treats it as being special, and even that can be adjusted.

Additional context
Gutenberg v3.4.0