No it didn't, that is fake news. Please provide an unbiased source where JD Vance claims the US will be paying Iran $300 billion.
"Well, Ed, that's the sort of thing they could have access to, funded by the Gulf coast coalition, so long as they honor their end of the obligation. I think that one of the things you're going to see, Ed—and people have to be skeptical of this—is that the hardliners in the Iranian system will overemphasize the benefits that Iran gets, while underemphasizing all the things that they have to concede and all the things they have to provide in order to get these benefits," Vance replied.
NBC news. He said the "Gulf Coast coalition", but it's unclear exactly who is going to be paying into that.
Very cool and worthwhile way to spend your one fleeting existence dude: https://news.ycombinator.com/item?id=48446644