You learn something new every day: part of Section 311 Special Measure 5 (at least in this case) requires firms to notify customers who have correspondent banking accounts that the targeted parties may not have use of or access to the account.
[UPDATE] Here is the notice FinCEN just sent:
FinCEN Requests Comments on Renewal of the OMB Control Number for Bank Secrecy Act Requirements in Connection With the Imposition of a Special Measure Concerning North Korea as a Jurisdiction of Primary Money Laundering Concern
On November 4, 2022, the Financial Crimes Enforcement Network (FinCEN) published in the Federal Register a 60-day notice to renew the Office of Management and Budget (OMB) control number assigned to existing Bank Secrecy Act regulations at 31 CFR 1010.659. Specifically, the regulations require that U.S. financial institutions take reasonable steps to not process transactions through the correspondent account of a foreign bank in the United States, if such transactions involve a North Korean financial institution, and require institutions to apply special due diligence to guard against the use of correspondent accounts by North Korean financial institutions. The notice is required to give the public an opportunity to comment on existing regulatory requirements and burden estimates. The notice requests feedback from industry on or before January 3, 2023. FinCEN encourages the public to review this notice and provide comment.FinCEN Notice