Hi there,
You may know the 2D sprite editor Aseprite, which until recently was licensed under the GPLv2 (with a CLA), with binaries sold on the official website and on Steam. It was actually one of my references for a successful open source business model, as Aseprite is quite popular and most users are buying the binary version even though they could technically build from source.
A few days ago, the main developer (and full copyright owner, thanks to his CLA) replaced the GPLv2 licensed by his proprietary EULA, effectively making Aseprite proprietary. The source code is still available on GitHub, but it's now "shared source" and no longer "open source" (contrarily to what the README.md still stays as of this writing, but I don't want to sign the CLA to make a PR ).
With some Godot folks, we were quite stunned when we discovered the news today and decided to fork Aseprite at its last GPLv2 commit. You can find this new fork here: https://github.com/aseprite-gpl/aseprite
Our purpose is still not precisely defined, and is being discussed in this issue: https://github.com/aseprite-gpl/aseprite/issues/1
You are welcome to take part in the discussion, especially if you're interested in contributing to maintaining or further developing a libre community version of Aseprite.
As I mentioned in the above linked discussion, my purpose with this fork is first to gather all interested parties in one place, so that a community decision can be made about the future we want to give to Aseprite. So please partake in the discussion, express your opinion, and we'll see together how it goes.
As for the reasons that pushed the copyright holder to relicense, I must say that they are far from convincing. See this Twitter conversation for details about the (IMO) impulsive change. We should give it time though, as it could be that the author changes his mind and goes back to the GPLv2. Of course the CLA makes it hard for this project to thrive under the open source models we affectionate, but well we've also seen lone devs making a great job and producing software that benefits the community as a whole, so why not.