The free models are subject to tighter rate limiting.

They also offer free models like Quasar Alpha where they don't disclose who the model provider is. In exchange for you getting a capable model for free they get to log everything to improve upon it before a proper public release. Whatever that means, as I would expect everything and your mother to be logged and used for further training anyway.

Almost all of the free model providers out there say they can log your prompts. For example, I looked at the link you posted.

"To our knowledge, this provider may use your prompts and completions to train new models."