The Guardian also has it, and refers to the Bloomberg quote: https://www.theguardian.com/world/2025/oct/10/nobel-peace-prize-bets-polymarket
Archive of the Bloomberg article https://archive.ph/yC3EY which says
The story was first reported by local newspapers Aftenposten and Finansavisen. Three accounts at Polymarket that had mainly placed bets on Machado, made a combined profit of about $90,000, according to Finansavisen.
The Guardian just mentions Trump as earlier being behind Yulia Navalnaya, the economist and widow of former Russian opposition leader Alexei Navalny, who had been an earlier(individual) favourite. Bloomberg has a graph showing that - and also notes
Polymarket agreed with regulators to stop serving US-based users in 2022 because it wasnt a registered exchange. A week after the 2024 presidential election, one that Polymarket users wagered more than $3 billion on, its founder Shayne Coplans apartment was raided by FBI agents.
After Trump took office, the federal probe was dropped, although Polymarket, still doesnt allow US residents to trade on its website