That is orthogonal to having another citizenship, it affects anybody with just the US citizenship as same as somebody with a citizenship in every other country

That is orthogonal to having another citizenship, it affects anybody with just the US citizenship as same as somebody with a citizenship in every other country in the world all at once. >Tax implications only really affect you at high income levels (think millions of USD/annually). Depends on what you mean by "really affect" because they definitely affect you at any income level as you have to file taxes with the IRS.