I think OP might be referring to synthetic data, which is now used to provide more data for training?

That would makes sense. This is how AlphaGo became better then the training data, and was the basis for Alpha Zero which used no human data and became even better.

However the loss function (or the success criteria more broadly) for the game of go is extremely simple. We do not know whether such a success criteria even exists for a generic task like coding, and it is a mistake to assume that the AI labs have found one.