As pointed out in the github discussion, Elastic did the same thing with Elasticsearch, and that contributed to AWS forking the project: https://aws.amazon.com/blogs/opensource/keeping-open-source-...
The same exact issue applies here:
> The maintainers of open source projects have the responsibility of keeping the source distribution open to everyone and not changing the rules midstream
> we believe that maintainers of an open source project have a responsibility to ensure that the primary open source distribution remains open and free of proprietary code
Those comments aren't an indictment of the open core business model or of attempts to monetize open source, but rather a criticism of "muddying the waters" and trying to create licensing confusion.