Note serial numbers would prove this most likely scenario sufficiently for even the most opaque mind.
The bar code would tell you where it originated.
The bag itself probably indicates where it originated.
But my point is that reserves are sent to banks all over the world. So Bank A in, say Switzerland, needs to up its cash reserves, so they need $100k in physical dollars. They reach out to the Fed and they are sent bags of currency.
If someone comes in an wants bags of $100k in currency, the bank would make that transaction. After that, the person holding the cash can load it onto a private jet and literally move it anywhere.
Another possible source is the printing offices of North Korea. They are notorious for printing counterfeit $100 bills.
The cash itself means nothing unless you can track the specific bar coded bags to a specific depositor. And we never tracked the bar codes when transferring bags of dollars (not THIS big, but $20s and $10s) to depositors. They were scanned out of the vault and put into the trucks.