If the product is free, you are the product.
It means (to me at least) that if you agree to use a free service, expect you data to be "stole" and used.
GDPR cover a lot on how online service can use your data. Especially, you should be able to delete everything about you. I don't think Terms and Conditions can break GDPR, not sure I'm a not a lawyer.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.