Seems to me it's only guilty of the same data scraping for marketing purposes that Meta is... maybe even less so as I always found TikToks advertising less gross than Instagrams.
Both suck but TikTok is slightly less suck.
Is it really a security thing or is it a "We are getting pressure from US companies to remove competition" thing?
I'm sure it's only seen as a security threat because they can't lean on them the way they can U.S. based companies to control narratives and only push approved propaganda.