The US dollar as the main currency of international trade,
the rising or falling impact the international trade a lot,
When the dollar appreciates, you will spend less money to buy the same quality goods; otherwise, you will spend more money

For example: the same quality of a PVC raincoat in China purchasing cost is RMB 14 in 2020, as exchange rate, dollar/yuan rate us $1 = 7 CNY,it only need $2 
when exports in January 2021, exchange rate,  dollar/yuan rate is 1 usd = 6.4 RMB, then you will pay $2.18,an increase of $0.18 in January last year
For bulk order, usually an order is order thousands of pieces, even hundreds of thousands of pieces, so it not just $0.18

Of course the fluctuations in a short period of time is very small,
usually a quarter or a year period will have significant change, but some customers purchasing plan time is longer than the exchange rate change cycle
For example, an inquiry start in January 2020, but order placed in October 2020,
when the purchasing cost will be different,that will effect your order plan or increase the purchase cost.

So as an international trader, we will suggest the seller to make the decision on time. to avoid unnecessary losses