Robinhood is not free. You are paying through PfOF. Just because you're not aware that you're paying more for your trades doesn't mean it's actually free. And,

Robinhood is not free. You are paying through PfOF. Just because you're not aware that you're paying more for your trades doesn't mean it's actually free. And, as others have pointed out, they have a version of their service which is paid and is exhibiting the same behavior.