Since you refer to the darkweb. The gov has extensivley studied Tor and likely has zero day exploits for the Tor browser and operates a bunch of Tor relays. Given enough time and effort it is very much possible for state actors to identify Tor users.
But unless you are a high profile gov target, Tor protects you well.
Well it is of course not possible to 100% prove that Tor protects your privacy.
But the lack of evidence is also evidence. While we have evidence that the gov was able to identify indiviuals using Tor e.g. hosting drug portals, there has been no reports that individuals or companies are able to de-anonymize Tor users.
How often do we read articles about authorities attempting to unmask suspected criminals? That the FBI is trying to identify this person seems to be noteworthy to the point that there are many people here commenting on the story, and the fact that they are trying and have not yet seems to indicate that it is not a forgone conclusion.