Marcus Robinson, a 29-year-old fashion designer, created a Red Note account to share his thrifting adventures and promote his clothing company, P-13. He previously had accrued 21,000 followers on TikTok, and estimates that 40% of his brand’s sales came from that app. “I thought I was going to keep building and make a living ultimately,” he says.

As Supreme Court justices ponder the future of TikTok in the United States, a growing number of American social media users have responded by moving to an unlikely alternative: Xiaohongshu, a hugely popular social media app in China.