Extending Tribal Broadband Priority Act of 2021 This bill requires the Federal Communications Commission (FCC) to, within 30 days, establish a new tribal priority window for the 2.5 gigahertz band, through which tribes in rural areas may apply for unassigned spectrum. The new window is subject to the same terms and conditions as the tribal priority window that was adopted by the FCC on July 10, 2019, and that closed on September 2, 2020.