We got rid of the plugin tag some years ago (Burn the "plugin" tag).
Now there is the plug-in tag.
As it’s used on more than 20 questions, I guess it would be best that a mod deletes the tag, instead of editing (and pushing to the front page) all these questions to remove the tag.
(I edited the only question that had no other tag in addition, so now no question would end up being untagged.)