These trade deficits are self-reinforcing rather than planned. It’s not like the global reserve country necessarily decides to have persistent trade deficits. Using the United States as an example, if the whole world agrees or is forced to mainly use dollars to buy commodities and settle the majority of international deals, then there is naturally

The Triffin Dilemma Unfolds

In the 1960’s, economist Robert Triffin noted that global reserve currencies have to run large persistent trade deficits, which has been coined the Triffin Dilemma. If the reserve country doesn’t supply the world with a lot of their currency, then the world simply can’t use that currency for international trade, commodity

And for decades since then, the United States has had a current account deficit. It reached 3% of GDP in the mid-1980’s until the Plaza Accord purposely reduced the dollar’s strength, which helped fix the deficit briefly. Then it spiked to 6% of GDP but the self-correcting force of the subprime mortgage crisis reduced that back down a bit.