In March 2020, The Intercept obtained documents showing that the platform’s moderators were instructed to suppress posts by “ugly” and “poor” people and censor political speech in TikTok live streams. In November 2020, Insider reported that according to a senior TikTok executive in the U.K., the company censored content critical of China, specifically concerning the Uighur situation, but claimed it is not doing that anymore.
There are many concerns about TikTok's effects on users' attention span and mental health. One of the few studies on the issue was done by ByteDance, the parent company of TikTok. They analyzed users of Douyin, the TikTok equivalent in China.
As The Wall Street Journal reported, the study showed that “areas involved in addiction were highly activated in those (students) who watched personalized videos. It also found some people have trouble controlling when to stop watching.” A pediatrician quoted for the article called TikTok a “dopamine machine.”
In May 2022, The Wall Street Journal published a piece called "TikTok’s Work Culture: Anxiety, Secrecy and Relentless Pressure". They reported that TikTok employees “many of them veterans of other major tech companies, say TikTok emphasizes relentless productivity and secrecy to a degree uncommon in the industry.” Former U.S. staffers told of sleep deprivation, work on weekends and mandatory meetings with colleagues on the other side of the globe
In October 2021, The Intercept reported the case of workers in Brazil spending up to 90 hours per week transcribing TikTok videos and getting paid 70 cents an hour – half the minimum wage, even though the company is worth $75 billion.