The Ohio State football team had to play multiple games against Michigan while they were using signs illegally obtained through a sign-stealing scandal. Connor Stalions was at the center of the scandal, as he illegally scouted opponents in person.
The Ohio State Buckeyes weren't the only opponents that TTUN used these signs against. Stalions essentially scouted every single opponent that Michigan was facing for the better part of two years. It's part of the reason why Central Michigan is now being investigated after he was caught being on the sidelines.
After two years of investigating, interviewing many people, and getting Michigan's response, the NCAA has finally decided to release its findings to the public.