The version they contributed to is still available under the same permissive license that was in effect when they were contributing the code.

The license change only affects the code written in the future and now people can change their mind about contributing.

That seems fair to me.

Maybe you think that morally the license should never change but there is no clause in the license to prevent changing the license, so that would not be a reasonable expectation.

What percentage of commits were made by community developers?

The company Redis only adopted the Redis project (and changed its name) a few years ago. Redis started as a community project and was run that way for almost a decade.

Why should that matter? I'm sure the percentage would be way smaller if this was the license used initially.

All clients will still be Open Source and a lot were initially written by the community as far as I'm aware, so they're actually still asking for free labor there.

About 75% afaik.

They contributed free labour under a licence that says that anyone can do anything they want, including offering it under a different licence.

This shows a fundamental misunderstanding of how open source licenses work. I am completely sick of this take. It’s intellectually dishonest, or extremely ignorant.

Never attribute to malice that which can be explained by stupidity

Reading the other comments the switch does make more sense, if you want to freeload off of the work redis has done for the project then you’ll have to join whatever community remains on the forked version, and anyone who cares about this kind of stuff should probably understand what’s permissible in the previous license, which clearly includes it being switched out like this