The communications blackout that never covered monetary transactions, letting Rosetta move billions freely.
Orren tells the Syndicate prime minister flatly that monetary transactions aren't covered in the communications blackout, and reminds him that this was the council's own decision, taken despite liaison advice against it. Because of that gap, Rosetta was able to route King Rust's fortune through Colloid Bank onto a Credit Chit and out again with nothing to stop her.
The blackout otherwise still holds, isolating the crawl and the system while cruisers exchange fire in orbit and the Syndicate Council argues over money that is already gone.
The information lockdown whose loophole enabled the largest theft in the crawl.