The Elastic blog post announcing the change never says exactly those words, but it repeatedly talks about being an "open source company" with an "open source product" -- despite the fact that Elasticsearch is now available under a choice of two different licenses, neither of which is "open source" under any reasonable definition.
(The other option, the Elastic License, allows you to use the product in either source or binary form, but you may not make derivative works or compile your own binaries except for testing.)
On the license there are 3 main "propagation" clauses: Conveying Verbatim Copies / Conveying Modified Source Versions / Conveying Non-Source Forms
Furthermore: Acceptance Not Required for Having Copies / Automatic Licensing of Downstream Recipients
On the other hand, the "issue" seems to be an Aferro-like clause that conveying it as a service combined/linked with other software over a network _counts_ as distribution an gives a right to the users to request the source code that makes the service work.
(The other option, the Elastic License, allows you to use the product in either source or binary form, but you may not make derivative works or compile your own binaries except for testing.)