> The SSPL allows free and unrestricted use and modification, with the simple requirement that if you provide the product as a service to others, you must also publicly release any modifications as well as the source code of your management layers under SSPL."

The magic is in the "management layers" part. True copyleft says "you can use this software in your product but you have to open source any changes to the software". Okay, fine. This "poison pill proprietary license dressed up as copyleft" is saying "if you sell a service that uses an UNMODIFIED version of elasticsearch, you have to release every piece of software around elasticsearch, including your hypervisors, kernels, os image...the list goes on". It's very clearly an attempt to make the requirement so odious that no-one would risk triggering that clause.

Which is why functionally all they did was force Amazon (and other organizations like Wikimedia who don't sell Elasticsearch as a service but do refuse to run proprietary software) to have to fork.