TikTok ban is upheld by Supreme Court in a unanimous decision.

• The Supreme Court has ruled to uphold the TikTok ban.
• It's uncertain whether third-party internet service providers will back the app even if President-elect Donald Trump decides not to enforce the law.
• After the deadline, TikTok will be penalized if companies like Apple and Google continue to support it, as per the law.

On Friday, the Supreme Court ruled that ByteDance must sell its stake in TikTok by Sunday or face a complete ban of the app in the U.S.

If ByteDance continues to refuse to sell TikTok, many U.S. users could lose access to the app this weekend. The app may still function for those who already have it installed, but ByteDance has also threatened to shut it down.

The Supreme Court unanimously upheld the Protecting Americans from Foreign Adversary Controlled Applications Act, which President Joe Biden signed in April.

"The Supreme Court's opinion stated that TikTok offers a unique and extensive platform for expression, engagement, and community for more than 170 million Americans. However, Congress has decided that divestiture is necessary to address its legitimate national security concerns about TikTok's data collection practices and ties with a foreign adversary."

TikTok's vast data collection and susceptibility to foreign adversary control pose a national security concern, according to Supreme Court Justices Sonia Sotomayor and Neil Gorsuch.

After the Jan. 19 deadline, third-party internet service providers like and will face penalties for supporting ByteDance-owned TikTok.

If internet service providers and app store owners comply, they will remove TikTok from their respective app stores, preventing users from downloading TikTok or installing the necessary updates that make the app functional. White House press secretary Karine Jean-Pierre reiterated President Biden's support for the law in a statement, saying "TikTok should remain available to Americans, but simply under American ownership or other ownership that addresses the national security concerns identified by Congress in developing this law."

Pierre stated that due to the timing, the current Administration acknowledges that implementing the law is the responsibility of the next Administration, which begins on Monday.

TikTok users in the US and worldwide will have their free expression harmed by the Supreme Court's decision, as stated by Kate Ruane, director of the Center for Democracy and Technology non-profit.

The First Amendment aims to safeguard the expression of individuals who use an app to create, share information, receive news, comment on current issues, and promote their businesses.

The future of TikTok in the U.S. is now in the hands of President-elect Donald Trump, who in December requested the Supreme Court to halt the law's implementation and give his administration the chance to resolve the issues politically.

On Monday, one day after the TikTok deadline for a sale, Trump will be inaugurated and TikTok CEO Shou Chew is among the tech leaders expected to be present, seated on the dais.

In December, the House Select Committee on the Chinese Communist Party wrote to Apple CEO Tim Cook and Google CEO Sundar Pichai, requesting that they begin preparing to adhere to the law and reminded them of their responsibilities as app store operators.

Last Friday, the Supreme Court listened to arguments from TikTok's lawyer, content creators, and the U.S. government regarding the app's ban. TikTok's lead lawyer, Noel Francisco, argued that the ban violates the First Amendment rights of the app's 170 million American users. In contrast, U.S. Solicitor General Elizabeth Prelogar contended that the app's alleged ties to the People's Republic of China via its parent ByteDance pose a national security threat.

Following the conclusion of oral arguments, several legal experts speculated that the Supreme Court seemed to lean towards the U.S. government's position regarding TikTok's potential ties to the Chinese government.

TikTok creators have been urging their followers to locate them on competing social media platforms such as YouTube and Facebook and Instagram, according to CNBC. Furthermore, Instagram executives held meetings following the Supreme Court hearing to instruct employees to prepare for an influx of users if the law is upheld, as reported by CNBC.

On Monday, RedNote, a TikTok-like Chinese social media app, became the top-ranked app on Apple's app store, indicating that TikTok's millions of users were searching for alternatives. Meanwhile, the Chinese government was reportedly considering a contingency plan that would have Elon Musk acquire TikTok's U.S. operations as part of several options aimed at keeping the app from being banned in the U.S. This plan was one of several being discussed as part of larger talks involving the upcoming Trump White House, according to Bloomberg News.

WATCH: SCOTUS hears TikTok ban case.