You're reading a lot into the article that isn't necessarily there. The WSJ didn't confirm that it knew of more than one supplier that was contacted, and Tesla's comment:
> But it confirmed it is seeking price reductions from suppliers for projects, some of which date back to 2016, and some of which final acceptance many not yet have occurred.
is quite ambiguous -- was that really a partial refund on past sales of parts for production cars? Or was it arm twisting related to failed or incomplete "projects"?
I don't know the answer, and I see a lot of people in this discussion being pretty enthusiastic about thinking they do know.