First of all, any company operating out of China can be assumed to be under more or less direct control of the CCP. When the Party comes knocking, there is no non-compliance to whatever they want. That alone is more than enough reason to be more skeptical of anything China. (Yes, I'm aware of FISA, but that's nowhere near comparable to having Party members on your board)
The second difference/risk comes with looking whom these apps target: kids. Basically, whoever controls the algorithm that ranks what content kids watch, has a very effective way of mind control... kids are sponges, they soak up whatever they see, and especially compared to the old radio/TV era, a lot of what's available on the Internet is pretty dangerous and not vetted by anyone. Be it all kinds of dangerous "challenges", Incel/Gamergate/far-right propaganda, hate against LGBT or whatever - it's all completely intransparent. That's bad enough if done by Western companies for profit reasons, but even worse as a capability in the hands of an enemy nation.