No it is not. Inflation would reduce their spending power, but additional money supply is a different thing.

Additionally, most "fixed incomes" these days are inflation pegged, so even inflation is not a burden. But it's never a tax.

But since you put it so starkly, it must be pointed out that when we do not deficit spend when we could, it is to the detriment of productive members of society that are producing all the things that those on fixed incomes need.