Social-media fortunes rose and fell on app stores this week.

Millions of Americans downloaded the Chinese social networking app Xiaohongshu as a possible U.S. prohibition of TikTok loomed. By late Friday, the app also known as RedNote led the Apple (AAPL) App Store’s list of top, free downloaded iPhone apps in the U.S. Other well-known social media apps, including Meta’s (META) Facebook and TikTok, were bumped from the top five. RedNote also topped the free table in Alphabet’s (GOOGL) Google Play store.

The Supreme Court on Friday upheld a law requiring ByteDance, TikTok’s parent company, to sell the platform or face a shutdown. Elected officials see the measure as a way to curtail national security risks presented by a Chinese-owned firm having data on the app’s roughly 170 million American users. U.S. groups could be fined for providing services or support to TikTok as soon as Sunday.

Enforcement, however, will likely fall to Donald Trump, who is slated to be sworn in as president on Monday. Trump on Friday said he has discussed TikTok with the Chinese President Xi Jinping, and needs time to review the situation. (If the ban holds, Morgan Stanley says, several U.S. companies could benefit.)

‘Xiaohongshu’ Is Having a Moment in the U.S.

Meanwhile, many Americans flocked to Xiaohongshu, which loosely translates to “Little Red Book” or “RedNote” and has traditionally been marketed to Mandarin speakers. RedNote shows videos in an infinite scroll—like TikTok does—and has a dedicated shopping section.

Although some of RedNote’s navigation features are in English, other text remains in Mandarin. (The number of Americans learning Mandarin through DuoLingo (DUOL) has recently boomed, the app said on X this week.) RedNote didn’t respond to Investopedia’s request for comment.

RedNote vaulted to the head of the Apple store’s list of top free apps Monday, joining household names like Instagram, Threads, TikTok and Facebook, according to market intelligence firm Sensor Tower. Millions joined RedNote during the five-day period ended Thursday, sending the app’s U.S. download rate up to 10 times its recent average, Sensor Tower said.

Other video apps, such as Flip and Clapper, along with Instagram also took off during the five-day period that ended on Thursday, Sensor Tower said, while Threads saw a slight decline in downloads.

The number of daily RedNote users in the U.S. hit 13.3 million—nearly 15% of TikTok’s domestic traffic—on Monday, according to Similarweb, a web traffic analysis group.

By Friday afternoon, TikTok, Facebook and Instagram were off the list of top five free iPhone apps in the U.S., according to Apple’s store. RedNote remained the leader, and other video-centric apps had moved into the top five, including Lemon8 and Clapper. (Those last two apps were also just behind RedNote in the Android store.)

Meanwhile, another app remained in the top 10 on both stores: TikTok.