Error when running localstack in kubernetes

Question

I've installed localstack using Helm:

https://artifacthub.io/packages/helm/localstack/localstack

The localstack chart was installed in its own localstack namespace, and I saw no errors in the localstack pod logs. In a different namespace I have a Spring Boot app (version 3.2.1), that needs to communicate with SQS in localstack. Here's the Sqs service:

package com.myapp.gateway.common;

import com.myapp.gateway.config.ConfigProperties;
import org.springframework.stereotype.Service;
import software.amazon.awssdk.services.sqs.SqsClient;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.sqs.model.ListQueuesRequest;
import software.amazon.awssdk.services.sqs.model.ListQueuesResponse;
import software.amazon.awssdk.services.sqs.model.SqsException;

import java.net.URI;

@Service
public class SqsService {

    private final SqsClient sqsClient;
    private final ConfigProperties configProperties;

    public SqsService(ConfigProperties configProperties) {
        this.configProperties = configProperties;
        this.sqsClient = SqsClient.builder()
            .endpointOverride(URI.create("http://localstack.localstack.svc.cluster.local"))
            .region(Region.of(configProperties.awsRegion()))
            .build();
}

public void listQueues() {

    System.out.println("\nList Queues:");

    try {
        ListQueuesRequest listQueuesRequest = ListQueuesRequest.builder().build();
        ListQueuesResponse listQueuesResponse = sqsClient.listQueues(listQueuesRequest);

        for (String url : listQueuesResponse.queueUrls()) {
            System.out.println("Queue url: " + url);
        }

    } catch (SqsException e) {
        System.err.println(
                "SqsException: "
                        + "getMessage: "
                        + e.getMessage()
                        + " | sdkHttpResponse.statusCode: "
                        + e.awsErrorDetails().sdkHttpResponse().statusCode()
                        + " | sdkHttpResponse.statusText: "
                        + e.awsErrorDetails().sdkHttpResponse().statusText()
            );
        }
    }
}

As you see, I'm using the localstack service FQDN, but my service logs show the following:

List Queues:
SqsException: getMessage: Service returned HTTP status code 403 (Service: Sqs, Status Code: 
403, Request ID: null) | sdkHttpResponse.statusCode: 403 | sdkHttpResponse.statusText: 
Optional[connecting to localstack.localstack.svc.cluster.local:80: resolving host 
localstack.localstack.svc.cluster.local: lookup localstack.localstack.svc.cluster.local: no 
such host]

It is not clear why this is happening, because when I kubectl exec into my service container and run:

nc -zv localstack.localstack.svc.cluster.local 80

I get:

localstack.localstack.svc.cluster.local (10.104.143.32:80) open

Port 4566 is also open but it doesn't work either. What is the correct endpoint URL?