This is not good news. It's actually changed from being free to costing $10/month.
The productivity benefits are worth more than $10/month easily, but somehow I still don't want to pay for it... maybe it's because they're using public domain code to train the model.
Nitpick - they're not (just) using public domain code for training - they're using "publicly available sources, including code in public repositories on GitHub."[0]
This includes a lot of code under copyleft licenses, and possibly even more code under no license at all (implicitly All Rights Reserved). It's not obvious to me that it's ethical (or possibly even legal) to sell a model derived from code not in the public domain.