Referees in professional sports are strictly prohibited from betting on the games they officiate. Betting on sports by officials, including referees, is considered a serious violation of the integrity of the sport and is typically against the rules and regulations of the respective sports leagues and governing bodies.
For example, in the National Football League (NFL), the National Basketball Association (NBA), Major League Baseball (MLB), and the National Hockey League (NHL), among others, there are stringent policies in place that ban all game officials from betting on any games they are involved with, as well as on the outcomes of games within their respective leagues.
If a referee is found to have bet on a game, they can face severe penalties, including fines, suspensions, or even a permanent ban from officiating. These policies are in place to ensure that the officiating remains fair and unbiased, maintaining the credibility and trustworthiness of the sport.