TikTok creators took to the app to express their shock and dismay on Friday after a panel of federal judges unanimously upheld a new law that could lead to the popular Chinese-owned video app being banned in the United States by mid-January.

“I’m, like, shaking — I’m so mad, I’m so anxious, because TikTok changed my life,” Katie Wolf, a 38-year-old book editor in Charleston, S.C., said in a video she posted on Friday. She finds 80 percent of her clients through the app, she said, and does not know what she would do without it.

“It’s about to get stupid,” Alex Pearlman, a 40-year-old comedian in Philadelphia, said in another video. “We don’t know what’s going to stay monetized, we don’t know how the TikTok Shops are going to keep working,” he said, adding expletives for emphasis. He continued: “We’ve got 44 days until this app goes.”

“It’s for real this time, guys,” Nicole Brennan, a 26-year-old artist and content creator in New York City, said in a video she shared with her 450,000 followers. Holding a bagel and looking a bit like she was in shock, she urged her audience to follow her on Instagram and Bluesky.

To its more than 170 million users in the United States, TikTok is a source of news, entertainment and income — a cultural juggernaut that wields influence over practically every facet of American life. The outcry on Friday illuminated the gap between Washington politics and the broader American public, as many of TikTok’s users seemed to have only just begun to grasp that the app could be on its last legs in this country.

The most common response to Ms. Wolf’s video was one of disbelief, she said in an interview: “To be honest, I feel like most people just didn’t think it was going to happen.”