On Saturday, TikTok users in the United States scrolled through the app for what could be its final hours after the Supreme Court upheld a law that requires ByteDance, TikTok’s Chinese parent company, to sell the app by Sunday or otherwise face a ban.

The mood was relatively somber, at least by TikTok’s typically unserious standards.

Alix Earle, a content creator with 7.2 million followers who rose to fame on the app in 2022, posted tearful videos mourning the platform.

“I feel like I’m going Through heartbreak,” Ms. Earle wrote in one video. “This platform is more than an app or a job to me. I have so many Memories on here. I have posted every day for the past 6 years of my life. I’ve shared my friends, family, relationships, personal struggles, secrets.”

Ms. Earle added that she had been “in denial” about the ban. She wasn’t the only one.

In the days leading up to the Supreme Court’s ruling, the tone on the app was jokey and even optimistic as many users did not believe that TikTok, a platform with 170 million users in the United States, would actually be banned.

Some users posted satirical videos bidding farewell to their supposed Chinese spies, a play on a long-running TikTok joke that all American users are assigned agents of the Chinese government to spy on them through the app. Others offered instructions on how to use a virtual private network in hopes of circumventing the ban.

On Friday, the Supreme Court unanimously upheld the law that effectively bans TikTok in the United States. After the ruling, emotions on the app began to shift. While some users were still laughing, others started posting more earnestly.