### Elasticsearch Version

8.8.0-SNAPSHOT

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

MacOS

### Problem Description

API when called is returning invalid response, on the same data terms aggs query runs fine 

![image](https://user-images.githubusercontent.com/3505601/220749805-ddf0d735-60d5-4e45-85bf-941ea3076a3f.png)


When run as aggs query 

![image](https://user-images.githubusercontent.com/3505601/220764360-49f7b648-8b15-43cf-afe2-01bd62e8ebc5.png)


### Steps to Reproduce

Queries are mentioned above ^^

### Logs (if relevant)

_No response_
server/src/main/java/org/elasticsearch/index/mapper/flattened/FlattenedFieldMapper.java
}
        @Override
        public boolean mayExistInIndex(SearchExecutionContext context) {
            return context.fieldExistsInIndex(name());
        }
        @Override
        public Object valueForDisplay(Object value) {
            if (value == null) {
                return null;
            }
            BytesRef binaryValue = (BytesRef) value;
            return binaryValue.utf8ToString();
        }
        @Override
        public IndexFieldData.Builder fielddataBuilder(FieldDataContext fieldDataContext) {
            failIfNoDocValues();
            return new SortedSetOrdinalsIndexFieldData.Builder(
                name(),
                CoreValuesSourceType.KEYWORD,
                (dv, n) -> new FlattenedDocValuesField(FieldData.toString(dv), n)
            );
        }
        @Override
        public ValueFetcher valueFetcher(SearchExecutionContext context, String format) {
            return SourceValueFetcher.identity(name(), context, format);
        }
        @Override
        public MappedFieldType getChildFieldType(String childPath) {
            return new KeyedFlattenedFieldType(name(), childPath, this);
        }