The first time visiting a stack with the new follow mechanic, you get the "Get updates on questions and answers" popup.
If the "follow" link is clicked, there is strange behavior. Clicking the X on the "get updates" popup closes the "unfollow" popup and the "get updates" popup will not go away.
The workaround here is a page refresh, which will clear the "get updates" popup.
I'm using Chrome Version 80.0.3987.149 (Official Build) (64-bit) for Windows 10.