Safeguarding Americans' Private Records Act of 2020 This bill imposes limitations on investigative powers provided under the Foreign Intelligence Surveillance Act of 1978 (FISA), reauthorizes certain FISA programs, and makes related changes. Provisions include reauthorizing to December 15, 2023, FISA authority to obtain business records, but also repealing the power to use such authority to obtain records on an ongoing basis; excluding certain data, such as cell phone location, from FISA authority to access business records; establishing that nonpublic information collected under FISA authority may not be retained for more than three years unless the information includes foreign intelligence information; disallowing the use of FISA-collected business records for criminal, civil, or administrative proceedings except in certain instances, such as cases involving a specific cybersecurity threat from a foreign country; requiring a government entity to notify a targeted person that the entity intends to use in court business records collected under FISA; excluding cell site location and global positioning system information from FISA authority for using a pen register or trap and trace device to collect evidence; reauthorizing to December 15, 2023, the power to treat individual terrorists as foreign agents; expanding the powers of FISA court amicus curiae (outside parties appointed to assist in a case), such as by authorizing the amicus to refer a FISA court decision to the FISA Court of Review; and repealing the government's authority to use National Security Letters to obtain financial or communications records without a court order.