Where if you feed AI input in you only get garbage out and it just eats itself.

"Mad cow disease" would be an apt description - this is how BSE originated:

BSE is thought to occur due to an infection by a misfolded protein, known as a prion.[3][6] Cattle are believed to have been infected by being fed meat-and-bone meal that contained either the remains of cattle who spontaneously developed the disease or scrapie-infected sheep products.[3][7] The United Kingdom was afflicted with an outbreak of BSE and vCJD in the 1980s and 1990s. The outbreak increased throughout the UK due to the practice of feeding meat-and-bone meal to young calves of dairy cows.