### 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_
x-pack/plugin/mapper-constant-keyword/src/main/java/org/elasticsearch/xpack/constantkeyword/mapper/ConstantKeywordFieldMapper.java
CoreValuesSourceType.KEYWORD,
                (dv, n) -> new ConstantKeywordDocValuesField(FieldData.toString(dv), n)
            );
        }
        @Override
        public ValueFetcher valueFetcher(SearchExecutionContext context, String format) {
            if (format != null) {
                throw new IllegalArgumentException("Field [" + name() + "] of type [" + typeName() + "] doesn't support formats.");
            }
            return value == null ? (lookup, doc, ignoredValues) -> List.of() : (lookup, doc, ignoredValues) -> List.of(value);
        }
        @Override
        public TermsEnum getTerms(boolean caseInsensitive, String string, SearchExecutionContext queryShardContext, String searchAfter) {
            if (value == null) {
                return TermsEnum.EMPTY;
            }
            boolean matches = caseInsensitive
                ? value.toLowerCase(Locale.ROOT).startsWith(string.toLowerCase(Locale.ROOT))
                : value.startsWith(string);
            if (matches == false) {
                return TermsEnum.EMPTY;
            }
            if (searchAfter != null) {
                if (searchAfter.compareTo(value) >= 0) {
                    
                    return TermsEnum.EMPTY;
                }
            }
            return new SimpleTermCountEnum(value);
        }