Foreign Gain-of-Function Research Prevention Act of 2021 This bill prohibits the use of federal funds to conduct or support gain-of-function research involving potential pandemic pathogens by China, Russia, Iran, North Korea, or other foreign adversaries. Gain-of-function research is any research that is anticipated to confer an attribute on a pathogen to enhance its pathogenicity or transmissibility in mammals. If the Department of State finds that an entity has used funds for prohibited research, the entity may not receive any federal funding for a period of five years.