It’s unblinded because the subject is preparing the concoction under study. There is no way they can create a blind experiment if they’re the ones preparing the control. The placebo effect is nothing if not pernicious and cunning, able to exploit even the most subtle psychological signal - like minuscule differences in the amount of powder in a capsule.

Blinded studies have independent doctors prepare and dispense the candidate drug so they know whether its the real thing or a placebo, but their patients dont. In double blinded studies, neither the doctor nor the patient have any idea about what they’re getting because a third party prepares the drugs.