You want to go deep weeds, let’s go deep weeds.  Almost all of the conversations about the $6 billion given back to Iran have focused on the fungible aspect of money.  While true, that focus misses the key and essential point, where the money was delivered.

The captured $6 billion was held in a South Korean bank, the result of sanctions violations.  What the Biden/Blinken crew did, was move the money from South Korea to a bank in Qatar.