San Francisco Mayor London Breed’s political rivals are claiming that a lavish, A-list party she helped throw at the Democratic National Convention this week crossed ethical lines because it was paid for by a billionaire donor to her campaign.

Ripple co-founder Chris Larsen footed the bill for party participants at Tao nightclub in Chicago’s swanky River North neighborhood. He paid for the open bar, wagyu beef sliders, all-you-can-eat sushi, and more. The over-the-top, 500-person, invitation-only event was one of the hottest tickets in town during the four-day Democratic convention and featured a performance by The Killers.