I am assuming the question refers to U.S. Passports.I've managed a non-postal passport application acceptance facility since 2023. In that time, I have personally accepted more than 1,000 applications, each with proof of citizenship (either a birth certificate or a previously-issued passport) sent with the application.In that time, I have only encountered one individual who did not receive her proof of citizenship back. The good news, however, is that birth certificates are replaceable, and passports also serve as proof of citizenship and identity. So if you're the unlucky one in a thousand, you've still got options.