I noticed this displays a hovercard for the "Cancel" button on editing pages. This is rather odd behavior for the user. I'll leave it to you to decide whether that is an issue worth fixing or not.
Topic on Talk:Page Previews/Flow
The Navigation Popups gadget does this, too. I've filed Phab:T122078. Thanks. :-)
Submitted https://gerrit.wikimedia.org/r/#/c/260754/ :) Waiting for review.