The present-day patent office is a joke. They basically just rubber stamp whatever you send them, and do so in priority order of who knows how to play their elaborate and bizarre game of approval queue gaming.

On what grounds? That law firm successfully obtained a patent which (even if later invalidated) resulted in revenues for their client (the extortion money). That is not malpractice, it is SUCCESSFUL practice -- and more so if the patent is highly questionable, as it may have been the legal firm's skill that resulted in the patent being issued.

On the same grounds that lawyers are sanctioned for bringing frivolous or extortionate lawsuits.

I think you bring a poor strawman to the debate, its not a question of whether or not the lawyer was successful, its a question of whether they were working toward the betterment of the system. For example. doctors may be sued for malpractice for performing surgeries that are unneeded even though the surgery is completely successful. They violate the terms of their licensing in the state where they practice by doing so.

My point is that there are many ways to mitigate the perils of the patent system without destroying it. One is to make abuse of it to have some cost.

So a proposal might be like this [1]:

To prosecute a patent (represent an inventor as their attorney in the application process) requires licensing by the patent licensing bar. That license states that willfully bringing a patent before the commission that is found later to be invalidated, and such invalidation shows negligence on the part of the prosecuting attorney, that attorney or their firm, is co-liable for any charges or court costs incurred by the folks who invalidated the patent.

It would also be interesting in public shaming of people who claim to have 'invented' such preposterous things. That is a much more social thing though.

[1] I'm not a lawyer, and I know it doesn't work like this today, its a proposal to make it 'painful' to try to game the system as a lawyer.