> What do I mean by Fake Open Source? A project that has a large percentage of its contributors beholden to a single organization/entity to me is not really open source in spirit.

Then you should use a different term - something like "community project". The single organization projects are still open source, both technically and in spirit.

> I'm looking for a project where I can feel confident my contributions won't effectively end up behind some proprietary license down the line if/when the VC backed organization that primarily sponsors development decides it needs to protect itself from AWS.

If you're talking about ElasticSearch, I'll point out that Amazon forked it and OpenSearch is not behind a proprietary license, so all contributions made to ElasticSearch continue to be available as open source, with improvements being made.