Are you a large institution holding some unsightly positions, perhaps short on something, and would you believe it there is a liquidity test and you have to come up with cash, fast? How do you do it? The answer is simple, just debit a bunch of guys and then reverse the transactions.
Announcement of the liquidity test: https://www.dtcc.com/-/media/Files/pdf/2021/4/20/GOV1082-21.pdf
And so it’s a technical error, nothing illegal happening, and nothing to worry about. Once the liquidity test is completed, the funds will be reverted to their righteous owners. And hey, everybody turns out to be liquid!