It's actually 3X. TMV/TMF is even more volatile since it is for the 20 Year. Problem is the rate just keeps going higher and higher so all you need is TMV right now. Maybe the Fed will capitulate to the markets & decide to stop raising rates and TMF will make sense.
I mean it could happen if the inflation calms down or supply chain eases. I doubt it will happen but its always possible. I still remember 2018 Q4 and the Fed pretty much collapsed the industrials & tech stocks.