Protecting America's First Responders Act of 2021 This bill makes changes to the Public Safety Officers' Benefits (PSOB) program. The PSOB program provides death, disability, and education benefits to public safety officers and survivors of public safety officers who are killed in the line of duty or permanently disabled as a result of catastrophic injuries sustained in the line of duty. Among the changes, the bill expands the public safety officers eligible for coverage under the PSOB program to include firefighters whose primary duty during an emergency response is to secure the scene or manage traffic and cadets or trainees in candidate-officer training; extends coverage under the PSOB program to certain public safety officers responding outside their jurisdiction; increases the interim benefit amount payable on a claim for death benefits and requires the interim amount to be adjusted annually for inflation; increases the benefit amount payable on a death or disability claim that has been pending for more than 365 days on the date of the final determination; allows the Department of Justice (DOJ) to use investigative tools, including subpoenas, to expedite the processing of claims and obtain information or documentation from third parties (e.g., public agencies); specifies that an injury resulting from a neurocognitive disorder qualifies as a catastrophic injury for the purposes of disability benefits; requires (currently, authorizes) DOJ to provide retroactive education benefits to qualifying children and spouses; specifies that hearing officers appointed to review claims are special government employees (i.e., employees who perform temporary duties for a limited period of time) and are authorized to conduct examinations; allows responders to the World Trade Center or their surviving family members to file claims for death or disability benefits in certain circumstances; and extends the period during which public safety officers who die or become injured as a result of COVID-19 are eligible for benefits.