If the US gets invested with such "virtual" ("out-of-thin-air", newly issued, etc.) dollars i guess it would be even worse as it would only inflate prices in US while not doing anything else.

Maybe?

What we're discussing is clearly beyond my ability to grasp (macro-)economics.

Being the biggest reserve currency has a little-discussed perk where the reserves lower the average velocity of money, which blunts the inflationary pressure of money-printing. Eroding trust in the US will deplete these deep pools of USD and will result in a more direct linkage with domestic inflation in the future.

It is inflating prices but also doing a lot more contrary to nothing.