The recruiters for TikTok are great to work with and they are very personable. TikTok can move quite quickly once you do get to talk with a recruiter. However, it is very competitive to stand out and be noticed by a recruiter given how many applications they receive. Those who go above and beyond are rewarded for their effort.
TikTok will want to see that you've done your homework in researching the company's products and monetization strategy, that you're passionate about wanting to work at TikTok, and that you align with the company's values (on the company's website) and mission (to inspire creativity and bring joy).
There's no brain teasers or any trick questions, so focus on your answers to behavioral questions.
Overall, interviewing and working at TikTok has been a great experience. It's not for everyone as it's still very much a startup and you have to be able to adapt to change, but if you like being a builder, this is the place for you.