Earlier quoted context omitted.
I am not a lawyer. There's generally nothing stopping a copyright holder from ceasing their distribution under an old license, and starting distribution with a new one. However, detaro linked https://github.com/MetaMask/metamask-extension/issues/9285 which brings up that this new license probably violates the license terms of it's GPLv3 dependencies. Additionally, if they've accepted any pull requests without requiri…
Also technically I guess (IANAL) you might have to prove that you obtained the source code prior to the license change. We like to say code itself is licensed such and such, but in reality code is licensed to somebody. If you just place the code somewhere for a month with a license next to it and take it down again, and somebody later comes and wants to get those terms, it's probably too late. OTOH please correct me…
I don't see why. If some code is made available under an MIT license and then the copyright owner switches to a new license, nothing stops others from continuing to use the original code under the original license.
Of course to do this you would have to know the code exists, but you could learn about its existence after the license change from someone other than the copyright owner.