I wish they wouldn't call them "open source models". They aren't open source. They didn't publish the training data. They didn't publish the tools they used to train the model. They published the weights. It's an "open weight model", a term that it seems nearly everyone has agreed is appropriate. Why is this company not using it?
This trope was valid maybe in 2022. Model training now is not a straight forwards process of input data -> run tools -> get model. There's a whole lot of alchemy going on. We don't quite understand what works and what doesn't. Think of it like painting with water color and having to improvise very often. The only advantage over water color is that we can revert to a working state.
Really, it’s no more open source than a free calculator. It’s free, and you can use it to no or great effect. But, you sure as hell can’t make one.
So calling it open source is without question, wrong.