A license that requires source. And since then there have been many different licenses, all with the same requirement. Giving someone a binary for free and saying they’re allowed to edit the hex codes and redistribute it doesn’t mean it’s open source. A license to use and modify is necessary but not sufficient for something to be open source. You need to provide the source.
And the data is not available. Knowing the weights of a model doesn’t really tell us much about its training costs.