By design. Especially the format (short video clips) and the optimization for being used on phones (not computers) makes it attractive for kids.
63% of Americans between the ages of 12 and 17 used TikTok on a weekly basis
Report Estimates One-Third of TikTok Users Are Children Age 14 and Under
A Third of TikTok’s U.S. Users May Be 14 or Under, Raising Safety Questions
I tried googling, can’t find anything that supports these claims
Seriously? it took me one google search to find an endless list of such articles. Also, did you not notice all the kids outside filming Tik Tok dances with their phones, it has been going on for many years now, how is it possible you did not notice it?