Peace Corps Reauthorization Act of 2021 This bill reauthorizes through FY2025 and modifies operations of the Peace Corps. Changes include expanding benefits and services for volunteers by increasing the readjustment allowance paid to volunteers when their service terminates and providing statutory authority for an executive order that grants returned volunteers noncompetitive eligibility for federal civil-service positions. Additionally, the bill entitles returned volunteers to three months of health care benefits (and a three-month extension at the volunteer's expense). The Peace Corps must also provide volunteers with (1) information about enrolling in U.S. health plans no more than 30 days prior to service termination, (2) adequate access to menstrual products, and (3) mental health care during and after service. The bill also includes provisions to address involuntary termination of Peace Corps service in emergencies or otherwise through no fault of the volunteer, including by expediting re-enrollment of involuntarily terminated volunteers. The Peace Corps must also provide adequate support to insure volunteers' safety and must coordinate with the Department of State to periodically update agreements and plans concerning the security of Peace Corps volunteers and staff abroad. The bill also modifies the Peace Corps National Advisory Council's membership and functions, expands whistleblower protections for volunteers, increases the rate of pay that applies to a volunteer's workers compensation claim, and requires a focus on leveraging the internet in Peace Corps programs. Furthermore, the bill requires reporting on (1) Peace Corps operations in the Pacific Islands, and (2) the provision of mental health services to volunteers.