Earlier quoted context omitted.
This is about finances. If the US declares you a terrorist organization, you cannot do any banking anymore, even outside the US, since most banks do not want to gamble on SWIFT access. Since the US considers anything "antifa" as terrorism now, it already had most concerning distant effects last year. See GLS bank cancelling Rote Hilfe in Germany. 1933 was the last time Rote Hilfe was cancelled, btw. It's an antifa OG…
This OFAC action isn't based on "antifa", though the press release predictably takes shots at it. It's based on three designated foreign terrorist organizations, notably the PKK.
The US does not give a damn about PKK. They used the Kurdish sister organizations in Syria and Iran. They condemn PKK because Erdogan wants it.
The US would have zero issues with a Kurdish state comprising parts of Turkey and Iran that splinters the region even more.