I was retagging "signup-signon" questions, so paying more attention to tags than usual. And so I noticed the tag experience.
I don't see a use for it other than indicate that the question is about user experience, which is nonsensical on this site. Indeed, when I looked over the questions tagged with it, I saw no value of having it there.
My suggestion is that it should be handled by the team in the same way as the "user experience" tag was handled.