Maybe it's just leverage.
Treasury yields fell on the rout in global equities at the start of the month but they've since stayed down even with equities sizzling. Some of that is surely a picture of inflation that's placid but that's still tough to square.
Maybe the simple answer is the best one: People are in leveraged longs in a bet that Fed funds will fall.
It's not a great trade on the face of it but you can borrow at 5% right now and buy 10s paying 3.78%. That's cashflow negative but look out to December 2024 and Fed funds are trading at 3.56%, with more easing priced beyond.
Now this might not just be a Treasury trade but in the whole bond complex, with many issues well-above the cost of borrowing and the whole stack moving with it as part of the massive amounts of leverage and synthetic leverage in fixed income.
In short, it's just the market saying that it's confident in inflation and confident the Fed will get to 3% or lower.