Yes, it is. [0]
> it’s the federal prosecutor’s office.
That is among its functions, yes.
> The antitrust laws we have are quite old and passed during the era of robber barons in order to do something about them, with extremely broad language that by its terms would prohibit not only anything you might like them to but a lot of things you might not.
Among the antitrust laws we have are:
* the Antitrust Criminal Penalty Reform and Enhancement Permanent Extension Act (2020); whose main effect was, as the names suggests, to make permanent the provisions of the Antitrust Criminal Penalty Reform and Enhancement Act (2004).
* the Criminal Antitrust Anti-Retaliation Act (2020)
* the antitrust provisions of the Competitive Health Insurance Reform Act of 2020 (oddly enough, 2021)
Some of our antitrust laws were written in the so-called “age of robber barons”, but antitrust law (even purely statute law) hasn’t been static since.
[0] for illustration, https://www.justice.gov/opa/pr/justice-department-advances-p... ; you probably mean, though, that its not the rulemaking entity with regard to competition, since that’s mostly the FTC.