It's not just that. A bond's price is simply the sum of its discounted future cash flows. i.e. the coupon value divided by (1+) the interest rate. When interest rates rise, the price goes down.

The Fed will accept treasuries as collateral for face value loans to banks for 1 year as part of the announcement. The losers here will be bank shareholders (of underwater banks) because they will need to dilute themselves to make up the difference when the loan gets called unless they can find other ways to make money in the meantime.

You wouldn’t buy it at face value. That’s what it means to say that its value has fallen.