UNAM (National Autonomous University of Mexico), one of the most important universities of Mexico, tried (and failed) to use AI to help make its admission exam fully online for the first time.

Massive scale cheating ensues, and students get approved with 100% score at scales way higher than previous year. Applicants protest on both sides, some request that the exam gets invalidated, others ask for the results to be respected.

After an investigation, UNAM can't really know with certainty who cheated and who didn't, and the only fair option is to make the exam again in person, but only the people who approved and those with scores >= previous years approval scores.