Taxpayers. Imo if we didn't have such high national debt in the US, those interest payments to the debt could have instead been used for something like national health insurance. The politicians of the past really screwed us all with the debt.
There was a bit of a mitigating circumstance of COVID (for Trump and Biden), which caused the debt to jump for many countries as well (and not just the US), but it's not like Trump et co are helping the math along with all the tax cuts and asking for a US$ >1T military budget.