Earlier quoted context omitted.
Here's a study that performs analysis showing that tether prints the coins and someone at bitfinex uses them to buy BTC at optimal points to support it's price. https://onlinelibrary.wiley.com/doi/full/10.1111/jofi.12903
This can be explained as whales/institutions telling BFX "I want $100M of BTC" and a human OTC trader at BFX executing it optimally.
Remember this is newly printed tether which means net deposits of new actual usd, if you believe them - and of course I do not.