Look, if you have the world’s reserve currency, other countries will need to accumulate your currency. Every country needs dollars in their bank account (could be treasury securities or anything else priced and convertible to dollars).
You can’t conduct trade in dollars when your checking account has zero dollars.
So, to get dollars they sell us stuff. They need to sell us more stuff than they buy from us to get the dollars they need. Or they could buy the dollars on the foreign exchange market which just means other countries would have to sell us more stuff then they buy from us to get the dollars to sell on the foreign exchange markets.
Having the reserve currency means the really great thing that lots of people have to hold your currency, giving you real value to get it, and the difficult thing that domestic producers have to see more goods come in than go out. The goods have to come in so other countries have dollars to fill their checking account