A bunch of people from not-here decided they liked the myth of United States Steel and True-blooded American Labor more than they liked actual people working in the steel industry and companies that can actually make steel profitably in America.
The Biden administration bent of over backwards to accommodate the national USW who was at odds with the locals and very plainly colluding with Cleveland Cliffs to kill this deal. Nobody in the political class got the memo or even cared that they were only supposed to play hardball to get a better deal and that, in fact, US Steel was very happy to shut down all their steelmaking in PA and move their headquarters down south where they located their new, modern steel mill. And so we ended up here. Trump gets the win that Biden should have had.
Meanwhile the flames of thinly-veiled racism gets fanned in Democratic spaces because everybody needs to be polarized to whatever "their side" says and we end up with people somehow making the case that Japan, a country we have had a military defense treaty with for 65 years, is a security threat. A Japanese firm says they want to spend tens of billions of dollars to make steel in America and seemingly everybody, regardless of how much they say they want manufacturing in America, and regardless how much they say they support workers in America trip over themselves coming up with reasons why the ownership of that manufacturing must also be American. There is no charitable explanation.
As for the deal itself? All the investment and jobs commitments are more or less the same as the last deal offered during the Biden administration. All the "control" and "citizenship" provisions beyond the previously offered concessions are meaningless. US Steel will be a wholly owned subsidiary of Nippon Steel's already existing American subsidiary. And good. They certainly won't do a worse job running it than the previous management team.