Filter doesn't work

Users GraphQL
4

So for the query:

query MyQuery {
  queryCredentials {
    accessKey
    forUser {
      username
    }
  }
}

The result is:

"data": {
    "queryCredentials": [
      {
        "accessKey": "****",
        "forUser": {
          "username": "orch"
        }
      },
      {
        "accessKey": "****",
        "forUser": {
          "username": "orch"
        }
      },
      {
        "accessKey": "****",
        "forUser": {
          "username": "michal"
        }
      }
    ]
  }

No data was inserted with DQL, I used only slash API Explorer to run mutations