This is already probably pretty widespread in general. With the absolutely absurd amount of AI slop being thrown out on the web, and the insane amount of available training material for tiktok-slop....

Also, low effort tiktok-trend astroturfing videos are probably some of the easiest AI videos to mass generate. You need exactly zero original content, have massive amounts of training data available, and can easily make a prototype video that the AI can modify.