why is there a document with id '_search' in some indices?

[X-ration]

why are there some documents with id '_search' in some indices, while i didn't create them manually?

[X-ration]

it looks like:
{
"_index": "test_books",
"_id": "_search",
"_score": 1.0,
"_source": {
"query": {
"bool": {
"must": [],
"must_not": [],
"should": [
{
"match_all": {}
}
]
}
},
"from": 0,
"size": 50,
"sort": [],
"aggs": {},
"version": true
}
}

[X-ration]

es version 8.2.0

[DaveCTurner]

Thanks very much for your interest in Elasticsearch.

This appears to be a user question, and we'd like to direct these kinds of things to the Elasticsearch forum. If you can stop by there, we'd appreciate it. This allows us to use GitHub for verified bug reports, feature requests, and pull requests.

There's an active community in the forum that should be able to help get an answer to your question. As such, I hope you don't mind that I close this.