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Spring Boot will automatically register any Spring bean that extends Filter with the Servlet Container.

See Spring Boot documentation:

Registering Servlets, Filters, and Listeners as Spring Beans

Any Servlet, Filter, or servlet *Listener instance that is a Spring bean is registered with the embedded container.

Since your AppUserRegistrationFilter class is annotated with @Component, Spring will automatically create a singleton bean for the class, and it is therefore auto-registered with the Servlet container.

When you call http.addFilterAfter(new AppUserRegistrationFilter(appUserService), BearerTokenAuthenticationFilter.class);, you are manually creating another instance of the class, and manually registering the filter with the Servlet container.

Hence your code has registered two different instances of the class at the same time.

Solution: Don't call addFilterAfter() or remove the @Component annotation.