I don't know what you're looking for, or your level of intellect, so I copied/pasted the first few popular sources. It seems clear to me from these there are time limits and content restrictions on Douyin put in place by the CCCP for children in China under 14 to protect them from the detrimental effects of the platform. These limits are not in place for Western countries, presumably because China wants it that way, for reasons that could range from addicting children to the platform to using the platform for mass influence among Western youth. There are many more articles form different sources like this one, that you can find on your own if you are truly curious about this.

https://www.deseret.com/2022/11/24/23467181/difference-between-tik-tok-in-china-and-the-us

"Also, whatever restrictions China has for its citizens, is hardly a model worth following."

You mean how China gives kids time limits and only educational content instead of dance videos and soft porn? Please substantiate.

Do you know how to use Google?

search string: tiktok children china different educational

https://www.essentiallysports.com/nba-basketball-news-chinese-kids-using-smarter-tiktok-than-american-kids-shaquille-oneal-shares-popular-theory/

https://www.thatsmags.com/tianjin/post/33448/china-imposes-40-minute-daily-limit-for-children-on-tiktok

https://www.wizer-training.com/blog/what-is-chinas-youth-mode-version-of-tiktok

https://time.com/6099618/bytedance-tiktok-china-children/

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Took me 10 seconds, dude.

Imo, TikTok is "digital fentanyl" and should be banned from the US. The China version only has educational content whereas here it's loaded with addictive content that can negatively influence people.