Under the proposed plea agreement and diversion agreement, Biden would plead guilty to two misdemeanor tax charges and would be able to avoid punishment on a felony gun charge if he stayed out of trouble for two years. But at a tense court hearing, U.S. District Judge Maryellen Noreika questioned the constitutionality of the diversion agreement and refused to sign off on the deal, at least for now. Lawyers are due back in court in several weeks to revisit the issue.

Someone remind me who appointed that judge.

Definitely a Trump appointed judge, but my understanding is this was more on the attorneys not understanding what the agreement was and the Judge discovering while doing their due diligence on the plea deal. Hunter’s attorneys are likely to blame here.

How are his attorneys to blame?

The article linked doesn’t give a good recount of what transpired in the courtroom.

From the Axios article

But the judge’s questioning did reveal a disagreement over whether the agreement on the tax charges was linked to a gun charge against Biden. Prosecutors said it wasn’t; Biden’s team thought it was - and they repeatedly argued about it in open court.