This is an interesting question, and not one I have seen brought up in the Community Forum.
As far as I can tell, Upwork's information about "Featured Jobs" does not reference the concept of "refunds."
Can you tell us more about what you would like to see as a "refund" feature associated with Featured Jobs?
It sounds like you paid a one-time fee of $29.99 to have a job post featured with a special banner, and now you would like to have that money refunded back to you. Is that correct?