They are Regulatory fees assessed by the specific Broker for each transaction, unlike regular commission costs, this Regulatory fee is normally absorbed by the broker, but has instead been passed to the customer for their transaction. So in this case whomever is using a certain broker for a Block Position is in fact being assessed in shares per transaction for FINRA fees. It is called a Section 31 fee, and yes even the SEC applies such a fee per transaction.
The reason they started becoming numerous was due to the ODD LOT transaction reporting requirements, although the transaction is above the 100 share threshold currently it wasnt a requirement until December to report them.
It took 20 minutes to get an answer and pointed in the right direction, it has in fact been updated in the latest FINRA Trade Reporting Requirements: