That's because the license change by Elastic impacted not only Amazon, who could not provide Elasticsearch as a service anymore through its administrative consoles, but also all those vendors who were building APM/monitoring/log-aggregation solutions as-a-service on top of Elasticsearch. In fact, such vendors would typically use Elasticsearch as a back-end behind some custom UI.

So those vendors teamed up with AWS to develop OpenSearch.

Now last time I checked the commit history of the two projects, Elasticsearch had 3x more commits and many of them on cool new stuff, while OpenSearch focus seems to have remained on APM/log aggregation.

As someone who needs an actual "search engine", I am glad of the change, as I was worried OpenSearch may not be a viable open source alternative as it could be lagging behind in this domain.

Now I need to check what happens with the clients: will the client remain Apache License or will they change to AGPL? The latter would be a problem for closed source software.