People contributed to HashiCorp products - the software is not something solely made by HashiCorp. This might technically be legal under their CLA and indeed even in the absence of the CLA, under the Apache License, but it certainly isn’t fair to people who contributed to it voluntarily in the expectation it would form part of a Free software project.

I think maybe the best way to combat this type of thing in the future is if F/L/OSS communities (i.e. everyone who contributes to a project without being paid) starts: 1) preferencing copyleft projects over BSD/MIT type licenses, and 2) refusing to sign any kind of CLA (maybe with an exception for obligate non-profit organisations). Then, companies will either have to pick developing entirely at their own cost, or to accept contributions on the incoming=outgoing model, meaning they are also bound by the copyleft licence and are forced to keep it as Free software. That would end the bait-and-switch of getting people to work on your product for free and then saying “surprise suckers, it’s no longer Free software!”.