US sanctions law saying that you must not transfer X from the US to Iran, directly or indirectly, is reasonable. US sanctions law saying that you must not transfer X from Brazil to Iran is gross overreach. Yes, of course the US can apply its absurdly extraterritorial laws to any parent company in the US, just as Iran could penalise any Iranian company whose US subsidiary distributed a depiction of the prophet or whatever, but that doesn't make it good law or good practice.

That's a fair opinion to have.

But the US isn't really unique in applying their laws extraterritorially. See GDPR, Universal jurisdiction laws, China's National Security Law, etc... Every jurisdiction with sizable power does it. Some of these are even more extraterritorial in scope than US sanctions are.