Mister B.

TikTok uses a reaction-based algorithm, meaning the videos or streams you respond to will drive more videos and streams having the same content. Even when you mark videos as "Not Interested" and receive the response that they'll stop showing you videos like that again, they will and do.

While their community guidelines prohibit sexually-oriented discussions between adults and minors, TikTok pairs adults and minors in sexually-oriented discussions, leaving it up to hosts and moderators to assess a guest's age and remove them. When this happens, it is clear TikTok is aware of the subject and hand and the relative ages of the participants. They could prevent this using their technology, but they deliberately avoid doing so, and this leads to frequent bans from the platform, leading to my next point:

A ban culture. Anybody who has set up shop on TikTok is well familiar with being banned and going through the appeals process - that's how TikTok operates. Users need to be aware of the psychological effects of being on a system that sets you up for failure, bans you, and leaves you traumatized from an entirely preventable encounter. Furthermore, because the encounters are visible to all participants, they can be recorded and used to harm the reputation of the baited victim. This is how businesses and personalities are canceled, and a single misunderstood conflict could cause long-term damage to a person's reputation. It isn't worth the risk for teens or public figures operating without a professional/legal advisor.

Operates out of China - a country known to put strict controls over its citizens. While it hosts discord between polarized actors in an anonymous manner, one main attack users carry out against each other is doxxing - revealing the private details of an influential user to the general public. This comes with real-world risks and consequences. While it may seem like a safe place to share your ideological, philosophical, or political views, you must be aware that your real name, home address, and job details can be shared with your opponents at any time (and they are when users dox each other). China's government could use TikTok to carry out a legitimate cyberattack against whatever country it wants to by way of (among other things) doxxing.

Misinformation. By allowing anybody to behave as an independent news anchor, TikTok is loaded with false and reactionary information. A recently-introduced feature to re-publish old videos exacerbates the issue by allowing users to present last year's news as today's news. While some regard social media as the fastest way to get the "tea" (latest news), there are cases where a viral video is corrected days later by a professional who clarifies the misconception. That only happens when there's a professional willing to clarify the facts, and there are plenty of users who don't operate on facts and carry the misinformation forward.

Bots/trolls. No matter the subject, harmful behavior takes place on TikTok because bad actors easily work around TikTok's user controls. It can be spam, phishing attempts, political attacks, or other scams. Users must bring in their own moderators to manage their live streams, and if those moderators aren't in place, users are exposed to whatever gets in.

At the end of the day, TikTok is another social media app looking to monopolize end users' time and money while promoting the idea you can become wealthy by influencing others. You don't have to be honest, just, happy, fair... so long as you capture the attention of users and drive reactions, you can get paid (quite a lot for a select few and an unsustainable amount for everybody else).