The power crunch, on a scale unseen in more than a decade, highlights how some of Beijing’s changing policy priorities, including its effort to limit carbon emissions, can ripple through a global economy that has been reshaped by the pandemic.

“There’ll be a cascading effect,” said Mike Beckham, Oklahoma-based co-founder and CEO of Simple Modern, which makes products such as insulated water bottles and backpacks, “As we started to comprehend the ramifications of what’s happening, we realized that this is potentially bigger than anything we’ve seen in our business careers.”

Last week, one of Mr. Beckham’s main suppliers, based in Quzhou city in eastern China, was told by the local government that it could only operate four days a week, instead of the usual six. In addition, it must adhere to a power-usage cap, which cuts the capacity of the factory by about one-third as a result.

Mr. Beckham anticipates U.S. retail prices for many products could increase by as much as 15% next spring, as appetite from retailers stays strong.