USCIS.GOV https://www.uscis.gov/news/news-releases/putting-american-workers-first-uscis-announces-further-measures-detect-h-1b-visa-fraud-and-abuse

Employers who abuse the H-1B visa program negatively affect U.S. workers, decreasing wages and job opportunities as they import more foreign workers. To further deter and detect abuse, USCIS has established an email address which will allow individuals (including both American workers and H-1B workers who suspect they or others may be the victim of H-1B fraud or abuse) to submit tips, alleged violations and other relevant information about potential H-1B fraud or abuse. Information submitted to the email address will be used for investigations and referrals to law enforcement agencies for potential prosecution.