Olmo from AllenAI has been releasing their full pipelines including data [1]. A lot of it is just repackaged and resampled dumps from copyrighted data that has long been publicly available as dumps: Common Crawl, arxiv, Wikipedia, StackExchange, reddit --- all of which are presumably copyrighted with different licenses. Go in Huggingface and you can find massive multi TB data dumps used for pre training.
It is just as legal as when Uber and AirBNB were running illegal taxis and hotels during their growth phase. I'm just waiting for some corporate IP law firm to learn about Huggingface.