“I do know that nobody has confidence in buying its 30-year bonds. Maybe nobody wants its 15 year bonds now?”
I’m not sure what you are trying to say. The Fed buys (and sells) bonds issued by others (mostly the U.S. Treasury, but now also the private sector). It doesn’t issue its own bonds.
It basically means a repeat of the 70’s for America, where the feds had to offer higher interest rates to get bonds sold. Higher interest rates means high inflation. It also means high unemployment.