Each country has their own fiat currency that is inflationary. You can not find any national fiat currency that is not inflationary.

Combination of different fiat currencies make the work inflation, I don't think so, because the right question is, will their combination make the global inflation much worse?

I really don't think so as global macro economic depends mainly on biggest nations and economies. Inflation or hyper inflation in very small nations won't affect the global economy but if you see recession in a big country, the global economy will be in trouble.