Again, I have no clue whether this banana falls into this category, but generically and hyper-simplified: you have dirty money in a high-scrutiny jurisdiction, you buy a piece of art for $10MM, you move that piece of art to a more permissive jurisdiction and sell it for $8MM. That buyer gets a good deal and you just mostly cleaned $10MM for 20% in one transaction, which you can then layer into its now-local (permissive) economy for further cleaning before pulling it back out, apparently legitimately, to whatever jurisdiction you want.

You've avoided an international (currency) transaction of $10MM which would be flagged by pretty much every authority with oversight. Just two high-value domestic art sales, which happen all the time.