But it doesn’t seem to show up under the tags you’ve shown. Also, adding/removing a tag of the same name (in the area you suggested) seems to have 0 impact to the tag I used in issues.
My bad, i thought you were talking about tags to set on the project itself.
Well tags on issues work pretty much the same way : You add tags on your issue, if the last issue that has a given tag unselect it, then it’s automatically deleted.
You can unselect it in this dropdown :