Spring Boot 3, micrometer tracing duplicated traceIds

Question

I have a minimal Spring Boot webflux application with tracing: Demo2Application class:

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import reactor.core.publisher.Hooks;
import reactor.core.publisher.Mono;

@RestController
@SpringBootApplication
public class Demo2Application {

    private static final Log logger = LogFactory.getLog(Demo2Application.class);

    @RequestMapping("/")
    Mono<String> home() {
        logger.info("home() has been called");
        return Mono.just("Hello World!");
    }

    public static void main(String[] args) {
        Hooks.enableAutomaticContextPropagation();
        SpringApplication.run(Demo2Application.class, args);
    }
}

pom.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.1.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo2</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo2</name>
    <description>demo2</description>
    <properties>
        <java.version>17</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>io.micrometer</groupId>
            <artifactId>micrometer-tracing-bridge-brave</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

application.properties file:

management.tracing.sampling.probability=1.0
logging.pattern.level=%5p [${spring.application.name:},%X{traceId:-},%X{spanId:-}]

The issue that I am having is that after calling endpoint http://localhost:8080/ several times, in logs I can see duplicated trace ids for some of the requests. As far as I know, for every request a new trace id should be generated but it is not the case. Here is a screenshot with output where I highlighted duplicated trace ids:

I tried looking online for a reason why that happens but I didnt find an answer. Can someone explain this to me?