Group By Datetime fields While querying

[cybercom]

I need to group by day in my query, so i'm trying to apply group by with datetime field as below:

{
    "_source": "false",
    "query": {
        "match_all": {}
    },
    "aggs": {
        "group_by_weekday": {
            "date_histogram": {
                "field": "record_created_at",
                "calendar_interval": "day",
                "format": "EEEE"
            }
        }
    }
}

But i'm getting the results like below?

{
  "aggregations": {
    "group_by_weekday": {
      "buckets": [
        {
          "key_as_string": "Tuesday",
          "key": 1682380800000,
          "doc_count": 13
        },
        {
          "key_as_string": "Wednesday",
          "key": 1682467200000,
          "doc_count": 0
        },
        {
          "key_as_string": "Thursday",
          "key": 1682553600000,
          "doc_count": 1
        },
        {
          "key_as_string": "Wednesday",
          "key": 1683072000000,
          "doc_count": 1
        },
        {
          "key_as_string": "Thursday",
          "key": 1683158400000,
          "doc_count": 1
        }
      ]
    }
  }
}

seems like grouping is not being applied here

How can we do this other way to overcome this?