Most of these projects carefully distribute only the source code representation of the binaries, for this reason, relying on the consumer to acquire / own the art assets and copyrighted material (logos, trademarks, etc.).
Copyright for this new code is owned by the person doing decompilation. No one knows how similar to the original it is or not, just that it compiles to the same output.
Edit to clarify: by not exist, I mean it is not publicly available.
Also, If it is an unauthorized derivative work, as I understand it then it might not even qualify for copyright protection itself.
A reimplementation or a behavior-based clone is an entirely different legal world from decompilation.
In fact, the goal of most decomp not to produce the same binary, that’s just used as a validation.
True, but as a derivative work of the original source code they don't have rights to do anything with that code without infringing copyright.