Even leaving aside the question of whether the FBI actually compromised Tor, or just did something way more mundane like infect the defendant's PC with malware, the linked court document is really interesting.

Not only does the FBI decline to say how they determined what IP address the defendant used to access the Tor hidden service, but they're also trying to hide the fact that the defendant asked to see that information by requesting the court label the defendant's court filing itself a "highly sensitive document"? And the court granted that request? Is that normal? It seems really bizarre to me, but I'm not a lawyer.