Remember that in this story, as strange as this is to say, Amazon is the good guy. Elastic changed their products from a FOSS license to a proprietary one, and Amazon did exactly what you're supposed to do in that case: fork and continue development of the last FOSS version.
If I was a mole for Amazon working at Elasticsearch, I can’t think of a better way to accelerate the shift onto AWS’s offering than breaking client comparability with previous versions of Elasticsearch. If a customer needs to upgrade the client for some reason, they are forced to update the server as well. Maybe they’ll just update the client and server to OpenSearch while they’re at it so they don’t have any more forced updates in the future.
As far as I'm aware, this is the first major "hostile" fork AWS has done. In fact, it's probably one of the largest ones overall. It will be really interesting to see how this plays out in the long run.
While this is tangentially related to Amazon's fork of Elasticsearch, it's more related to Elastic's trademark infringement suit against AWS's use of the trademarked Elasticsearch name in their managed service, especially egregious given AWS's attempt to portray it as a "partnership" with Elastic in a since-deleted tweet:<p><a href="https://mobile.twitter.com/ppgosavi/status/1179181900969037826" rel="nofollow">https://mobile.twitter.com/ppgosavi/status/11791819009690378...</a>
So many people in this discussion take sides. The only thing I see, is divergence. APIs will now evolve separately, and compatibility will break soon. I think this competition and diversification will be good for innovation in search. But it’s also going to be confusing for a while. If you use Elasticsearch in Amazon, you better decide very quickly whether you want to hitch your wagon to the OpenSearch future. Migrating is going to be a pain in a year or two.