Protect DREAMer Confidentiality Act of 2021 This bill directs the Department of Homeland Security (DHS) to prevent disclosing information from applications to the Deferred Action for Childhood Arrivals (DACA) program to U.S. Immigration and Customs Enforcement (ICE) or U.S. Customs and Border Protection (CBP), except to implement the program. Application information may be shared only to identify or prevent fraudulent claims, for particularized national security purposes relating to the applicant, or to investigate or prosecute a felony not related to immigration status. The bill also prohibits DHS from referring any individual with deferred action status to ICE, CBP, the Department of Justice, or any law enforcement agency.