Profit is not the standard for the regulation of commerce in the United States though.
When the federal government set limits on crop production with the Constitution's Interstate Commerce Clause as its justification, Roscoe Filburn was simply growing wheat over the limit to feed his farm animals. That wheat was never sold, and it never crossed the property line to leave his farm, much less crossed state lines. The government still fined him and he lost his case in SCOTUS establishing precedent in Wickard v. Filburn, because it affected the market prices of wheat, despite the miniscule impact.
The same could be said of TikTok even if it doesn't earn a penny in profit.
When the federal government set limits on crop production with the Constitution's Interstate Commerce Clause as its justification, Roscoe Filburn was simply growing wheat over the limit to feed his farm animals. That wheat was never sold, and it never crossed the property line to leave his farm, much less crossed state lines. The government still fined him and he lost his case in SCOTUS establishing precedent in Wickard v. Filburn, because it affected the market prices of wheat, despite the miniscule impact.
The same could be said of TikTok even if it doesn't earn a penny in profit.