Renter Protection Act of 2021 This bill limits the use and availability of assistance provided under certain emergency rental assistance programs created in response to the COVID-19 pandemic. For example, rental assistance not yet used by grantees to assist eligible households as of July 1, 2021, must only be used for rental arrears after this date, and not for rent, utilities and home energy costs and arrears, or other expenses as allowed under current law. Further, the bill changes the deadline for distribution of these funds from September 30, 2022, to December 31, 2021.