The full document of interest is here. The title of this post is perhaps a little disingenuous, as for now they are asking for reporting of each single transaction under these definitions. But the direction is clear....

"The critical challenge is that Convertible Virtual Currency (CVC) mixing services rarely, if ever, provide to regulators or law enforcement the resulting transactional chain or information collected as part of the transaction.

Mixing does not, however, wholly rely on the use of CVC mixers. There are certain
methods that CVC users—and CVC mixers—often employ in an effort to obfuscate their transactions. These methods include:"

A. Pooling or aggregating CVC from multiple persons, wallets, addresses, or accounts: This method involves combining CVC from two or more persons into a single wallet or smart contract and, by pooling or aggregating that CVC, obfuscating the identity of both parties to the transaction by decreasing the probability of determining both intended persons for each unique transaction.

B. Splitting CVC for transmittal and transmitting the CVC through a series of independent transactions: This method involves splitting a single transaction from sender to receiver into multiple, smaller transactions, in a manner similar to structuring, to make transactions blend in with other, unrelated transactions on the blockchain occurring at the same time so as to not stand out, thereby decreasing the probability of determining both intended persons for each unique transaction.

C. Using programmatic or algorithmic code to coordinate, manage, or manipulate the structure of a transaction: This method involves the use of software that coordinates two or more persons’ transactions together in order to obfuscate the individual unique transactions by providing multiple potential outputs from a coordinated input, decreasing the probability of determining both intended persons for each unique transaction.

D. Creating and using single-use wallets, addresses, or accounts and sending CVC through these wallets, addresses, or accounts in a series of transactions: This method involves the use of single-use wallets, addresses, or accounts—colloquially known as a “peel chain”—in a series of unnatural transactions that have the purpose or effect of
obfuscating the source and destination of funds by volumetrically increasing the number of involved transactions, thereby decreasing the probability of determining both intended persons for each unique transaction.

E. Exchanging between types of CVC, or other digital assets: This method involves exchanges between two or more types of CVC or other digital assets—colloquially referred to as “chain hopping”—to facilitate transaction obfuscation by converting one CVC into a different CVC at least once before moving the funds to another service or platform thereby decreasing the probability of determining both intended persons for
each unique transaction.

F. Facilitating user-initiated delays in transactional activity: This method involves the use of software, programs, or other technology that programmatically carry out predetermined timed-delay of transactions by delaying the output of a transaction in order to make that transaction appear to be unrelated to transactional input, thereby decreasing the probability of determining both intended persons for each unique transaction.

Their 'logic' for enhanced reporting is here:

"FinCEN finds that reasonable grounds exist for concluding that transactions involving CVC mixing within or involving a jurisdiction outside the United States are a class of transactions that is of primary money laundering concern."

"FinCEN is concerned that CVC mixing makes CVC flows untraceable by law
enforcement and makes potentially suspicious transactions unreportable by responsible financial institutions—thereby fostering illicit activity as described elsewhere in this document."

"Furthermore, FinCEN assesses that the percentage of mixing activity attributed to illicit activity is increasing."

"FinCEN recognizes that there are legitimate reasons why responsible actors might want to conduct financial transactions in a secure and private manner given the amount of information available on public blockchains."

"FinCEN also recognizes that, in addition to illicit purposes, CVC mixing may be used for legitimate purposes, such as privacy enhancement for those who live under repressive regimes or wish to conduct licit transactions anonymously. Still, CVC mixing presents an acute money laundering risk because it shields information from responsible third parties, such as financial institutions and law enforcement"