### 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
public RootFlattenedFieldType fieldType() {
        return (RootFlattenedFieldType) super.fieldType();
    }
    @Override
    protected void parseCreateField(DocumentParserContext context) throws IOException {
        if (context.parser().currentToken() == XContentParser.Token.VALUE_NULL) {
            return;
        }
        if (mappedFieldType.isIndexed() == false && mappedFieldType.hasDocValues() == false) {
            context.parser().skipChildren();
            return;
        }
        XContentParser xContentParser = context.parser();
        try {
            
            context.path().setWithinLeafObject(true);
            context.doc().addAll(fieldParser.parse(xContentParser));
        } finally {
            context.path().setWithinLeafObject(false);
        }
        if (mappedFieldType.hasDocValues() == false) {
            context.addToFieldNames(fieldType().name());
        }
    }
    @Override
    public FieldMapper.Builder getMergeBuilder() {
        return new Builder(simpleName()).init(this);
    }
}