One of the queries that Synology makes

    <Marker>sdk-example/</Marker>
    <MaxKeys>1000</MaxKeys>
    <NextMarker>sdk-example/</NextMarker>

<?xml version="1.0" encoding="UTF-8"?>
<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
    <Name>sdk-example-kian</Name>
    <Prefix></Prefix>
    <Marker>Resilience_1.hbk/</Marker>
    <MaxKeys>1000</MaxKeys>
    <Delimiter>/</Delimiter>
    <EncodingType>url</EncodingType>
    <IsTruncated>false</IsTruncated>
</ListBucketResult>

/* s3 client setup */

await S3.send(new PutObjectCommand({ Bucket: "sdk-example", Key: "folder/foldertwo/file" }));

console.log(
  await S3.send(
    new ListObjectsCommand({
      Bucket: "sdk-example",
      Delimiter: "/",
      Prefix: "",
      Marker: "folder/",
    })
  )
);

  Delimiter: '/',
  IsTruncated: false,
  Marker: 'folder/',
  MaxKeys: 1000,
  Name: 'sdk-example-kian',
  Prefix: ''

  CommonPrefixes: [ { Prefix: 'folder/' } ],
  Delimiter: '/',
  IsTruncated: false,
  Marker: 'folder/',
  MaxKeys: 1000,
  Name: 'sdk-example',
  NextMarker: 'folder/',
  Prefix: ''