I don't want to link anything here but you can find the leaks online if you look for them including the Der spiegel article, some pretty compelling stuff. In a nutshell, most of City's sponsors are either Government owned or Government backed. SM is part of that government and chairs many of them himself. In short whenever City have had a shortfall they have been able to siphon money from other companies and inject it into the club, intentionally circumventing UEFA FFP rules and changing dates to suit to make it look like they didn't have a deficit. They are guilty on a technicality and if you look carefully the Club aren't even denying their guilt they are just not happy about the process.