It's the social media app which has come to define our perception of Gen Z, and which has firmly embedded itself within the Covid-era zeitgeist. A phenomenally popular platform, more than a billion users scroll through Tik Tok's endless feeds. But there's another side to the world's most popular app. From racist 'feeds' that erase people of colour, to videos promoting eating disorders, there's problematic content beneath the platform's playful exterior.