Two days before Christmas, TikTok called London-based journalist Cristina Criddle to tell her two of its employees in China, and two in the US, had viewed user data from her personal account without her knowledge or consent.
"It was just really chilling and horrible and, personally, quite violating," she says.
"I was at my family home with my teenage sister, teenage cousins - and they all use TikTok all of the time. They were like, 'Whoa, should we be worried?'".