Redistricting Transparency Act of 2021 This bill requires state redistricting entities to publish information regarding redistricting plans, both before and after adoption of a redistricting plan. The required information includes (1) maps of the congressional districts; (2) the composition of the districts by race, language minority group, and political party; (3) an explanation of the entity's reasoning for adopting the plan; and (4) any dissenting statements of the entity's members. Further, each state redistricting entity must maintain a website that provides redistricting plan information, meeting notices, and census data. The website must also allow individuals to submit comments and information.