Will TikTok become like Instagram, where 20 percent of the content consists of advertisements?

Eventually.. Yes

I'm pretty sure that more than 20% of content on my Instagram is Ads. 😿 Probably somewhere between 30-45%. (Especially high in stories) I have many times seen two ads back to back. On feed - Ads are often shown on the app's splash screen. They occupy the entire screen and force me to scroll to actually get any content. I really miss the old Instagram. I don't use TikTok, but eventually, Ads are the only viable way to make money off billions of people with the least churn. Thanks to Google for normalizing ads into our lives.

Well, eventually, yes.