Is not the interest that is not earned on public debt because of public policies a tax?

In terms of taxation, who is affected by a higher real tax rate?

Someone earning 5 percent in interest on public debt and, supposing a tax rate of 20 percent, then has to pay 1 percent in taxes, resulting in net earnings of 4 percent, or, 

Someone only earning only 3 percent on public debt, because of QEs, lower capital requirements for banks when lending to sovereign, and other fancy stuff causes lower interest rates on public debt.

You tell me, or better yet, tell them! on public