@tuk that id referrs to the index pattern ID. I dont know about elasticsearch 7.10, but opensearch does not query the index directly and always queries through the index pattern. There are two scenarios that come to mind here for me that could explain what you are seeing.
Elasticsearch allows for that field to support index id’s directly and opensearch does not
When you upgraded from elastic search to OpenSearch, the index pattern saved objects id’s did not stay the same or changed due to some underlying reason
I can tell you this, referring to an index directly is not supported in OpenSearch Dashboard’s right now. But if you update that o use an index pattern id, you should be good to go!
We do not want to query against index. We are using index pattern only (but name instead of id). In index:air-leg that I have mentioned in the question air-leg is an index pattern name.