According to USCIS "Applicants who filed their application for naturalization on or after Dec. 1, 2020, and before March 1, 2021, likely have been studying for the 2020 test; therefore, USCIS will give these applicants the option to take either the 2020 civics test or the 2008 civics test. There will be a transition period where both tests are being offered. The 2020 test will be phased out on April 19, 2021, for initial test takers. Applicants filing on or after March 1, 2021, will take the 2008 civics test."
The test items and study guides can be found on the Citizenship Resource Center on the USCIS website. USCIS has also updated the Policy Manual (PDF, 444.11 KB) accordingly; see Volume 12, Part E, English and Civics Testing and Exceptions, Chapter 2, English and Civics Testing.