It wasn’t Hunter Biden who pulled out of his plea bargain

So what happened? It's a little complicated. The deal had two parts: a Plea Agreement and a Diversion Agreement. The immunity provisions were in the Diversion Agreement.

This matters because it allows the Plea Agreement to be a "B agreement." Under a B agreement, the judge has no authority to accept or reject the plea. All she does is sentencing. However, if the immunity provisions were placed within the Plea Agreement—which is normal—then it would be an "A agreement" and the judge would have more authority over it.

The judge in the case implied that this was a bit of slick lawyering. She has no authority over the Diversion Agreement, which is solely a contract between Hunter and the government, and, because the immunity provisions were moved, she has no authority over the Plea Agreement either. So she's just a rubber stamp.

And there's more. The judge has no authority and no input into the Diversion Agreement, but it nonetheless includes a clause that makes her the arbiter of any alleged breaches in the agreement:

THE COURT: I'm concerned that that provision makes me a gatekeeper to criminal charges and puts me in the middle of a decision as to whether to bring a charge. And we already talked about separation of powers and that choice as to whether to bring charges is not — that's the executive branch, not the judicial branch, so is this even constitutional?

https://jabberwocking.com/it-wasnt-hunter-biden-who-pulled-out-of-his-plea-bargain/