US Treasury yields on longer dated bonds have been rising dramatically since the fall.
When the Fed "cuts rates" they lower the interest rates on very short term loans between large banks. The Fed controls the very short term interest rates in this way but the longer the loan the less control the Fed has over its interest rate, or yield.
So the yield on the ten year treasury bond is out of the Fed's control, its yield is determined by how much bond buyers are willing to pay for bonds. The more paid for the bond, the less profit the buyer will earn from the bond. In other words, the more paid the less the yield.
This matters worldwide, especially the ten year treasury bond, because of the continuing importance of the US Dollar in world reserve currencies. A great many international transactions are paid in dollars, so the buyer of say a shipload of crude oil must have dollars to pay for the shipment. Also other countries will keep US Treasuries as a way to stabilize their own currencies.
These Treasuries are how US government debt is financed. The yield on treasuries is (oversimply put for sake of space but roughly) the interest rate on the US national debt.
For a long time this interest rate was very low, but in the last few years it has risen from practically zero to what it is today. Long bond interest rates are affected by expectations of inflation. The more inflation expected, the more interest demanded by buyers.
So what will this new US government do, continue to spend like drunken sailors with credit cards or will they either lower spending or increase revenue, or both? Because more spending is financed now by inflation of the currency, which is money printing. Thats the big uncertainty in bond prices and one can see the market getting suspicious of the new regime.