当我使用Spring Security + WebFlux时，为什么对身份验证端点有双重请求？

@Bean
public RouterFunction<ServerResponse> routes() {
    return RouterFunctions.route()
            .GET("/auth", request -> handleAuth(request).deduplicate())
            .build();
}

@Bean
public RouterFunction<ServerResponse> routes() {
    return RouterFunctions.route()
            .GET("/auth", request -> handleAuth(request).cache())
            .build();
}

@Component
public class AuthFilter implements WebFilter {
    private static final String AUTH_FLAG = "authFlag";

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
        if (exchange.getAttribute(AUTH_FLAG) != null) {
            // 已经进行过身份验证，直接放行
            return chain.filter(exchange);
        } else {
            // 进行身份验证
            return authenticate(exchange)
                    .doOnSuccess(authResult -> exchange.getAttributes().put(AUTH_FLAG, true))
                    .flatMap(authResult -> chain.filter(exchange));
        }
    }

    private Mono<Authentication> authenticate(ServerWebExchange exchange) {
        // 身份验证逻辑
    }
}