Short answer: it sux and we hate it and it steals your information and sells it to commies.
Long answer: all video/ meme/ whatever apps steal alot of your info. They all harvest way more info than they need via cookies and use it to advertise to you. That's why after I buy a mattress I get six months of mattress ads on YouTube. Like I'm gonna buy 2 at once, lol.
Tik tok is different in that it's owned by a company that's owned by the Chinese Gov't. It's been caught multiple times harvesting location data, personal info, etc and sending it to China. There is no way this data is for something only mildly nefarious such as advertising or app quality control. The Chinese Gov't absolutely doesn't need this to place relevant ads in tiktok. Tiktok's stateside company could do that, easily. So tiktok is being used by foreign governments to spy on kids and steal their financial information. There are no non-malicious explanations for this.