Citizen Lab, my favorite security site, has published an analysis that is interesting but not very eye opening since I expected to see more on what it was sending back to China. My main objection to Tiktok is it is allowed in the U.S. but China will not allow Facebook there. There is no reciprocity in that kind of policy.
To read the analysis see https://citizenlab.ca/2021/03/tiktok-vs-douyin-security-privacy-analysis/
