Fallthrough proxy with Swagger-UI

I am using the latest version of the following dependencies:

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>3.4.3</version>
	<relativePath/>
</parent>
[...]
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
	<groupId>org.springdoc</groupId>
	<artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
	<version>2.8.5</version>
</dependency>

And the following configuration in application.yml

spring:
  cloud:
    gateway:
      routes:
        - id: legacy_proxy
          uri: http://localhost:8000
          predicates:
            - Path=/**
          filters:
            - RewritePath=/(?<segment>.*), /legacy-app-1/${segment}
          order: 1000

I have a controller:

@RestController
@RequestMapping("/example")
public class ExampleController {
    @GetMapping()
    public String getString() {
        return "test";
    }
}

When this application is running I can make requests to /example which hits the controller endpoint, and I can make requests to /some/other/path which proxies the request correctly to http://localhost:8000/legacy-app-1/some/other/path, but in this configuration I can not access /swagger-ui/index.html. Curiously not all Swagger endpoints are affected, I can access /v3/api-docs.

If I change to Path=/legacy/** then Swagger UI works correctly.

Any idea why the /swagger-ui/index.html path is affected like this?

Start by reproducing the routes in application.yml with Path=/** and then with Path=/legacy/**. Compare handling of /swagger-ui/index.html, /v3/api-docs, /example, and /some/other/path to trace the fallthrough proxy interaction. Done means the cause is identified and Swagger UI remains accessible without breaking the controller or legacy proxy paths.