This is from the Conn article.
One of the emails, from City’s then chief financial officer, Jorge Chumillas, headed “Cashflow”, stated that Mansour’s own company vehicle, the Abu Dhabi United Group (ADUG), would be paying £57m as a “contribution to 13/14 sponsorship fee”, while only £8m was Etihad’s “direct contribution”. Then Chumillas sent invoices for Etihad, internally to the City executives Ferran Soriano and Simon Pearce, stating that for 2015-16, the Etihad sponsorship was £67.5m, of which “£8m should be funded directly by Etihad and £59.5 [sic] by ADUG”.
The issue is whether ADUG paid City and we called it sponsorship, or Etihad paid City after ADUG paid them. If it's the latter then there cannot be a case to answer, as UEFA have absolutely no legislation where a sponsor gets their money.
If ADUG paid us, even on behalf of Etihad, things might get messy.