I would say it was already going on before the advent of tik tok, but I can't find a specific moment.

TikTok itself is part of the process. It was conceived in a pre-enshittified state. If MySpace was Lucky Charms, each new step along the way has been fundamentally a play of increasing the marshmallow ratio, until now it's perhaps (somehow, I'm not a cereal scientist) even higher than 100%:

MySpace -> Facebook -> Twitter -> Instagram -> TikTok