There’s a mystery afoot in New York City’s rental market, where the count of rent-stabilized units fell by 12 percent without explanation. There were 858,000 rent-regulated units registered with the state’s Division of Housing and Community Renewal as of November, down from 974,000 when the seminal Housing Stability and Tenant Protection Act was passed in 2019, The City reported. The drop came despite the law being designed to prevent landlords from deregulating vacant apartments after