Yeah that particular one is an actual lack of access and not something some math people came up with. They're exploiting a bug you'd need to know how the mechanic actually works for, which has not been described to the community.

I've unearthed what I assume is about 90% of LaF secrets about math they were given inside info on, and posted it all in an effort to increase parity. Unfortunately never learned what bug they exploit on essos tho, and it's been around forever. That particular exploit they hold tight to the chest, I'm assuming because it is an actual exploit and they'd get deleted for exploiting bugs if it came out what they do.

Been wrong before, but this one has always looked and smelled like fluff.

I've gotten close to understanding that it has SOMETHING to do with minimum sell prices where the market auto buys and back ended essos, but it's clearly a bug getting exploited they don't want changed because it's how they pump the dons.