> leading developers of Stockfish have terminated their GPL license with ChessBase permanently.

Can the developers do this? I was under the impression that when code is published on the web GPL licensed, the developers cannot retroactively withdraw the license...

Or perhaps they are withdrawing the license for all new code... To publish some code as "GPL, available for all except this person"? Is that allowed? Even if that were allowed, someone else could use their rights under the GPL to redistribute it to that person...