There's still a difference between "guessing" correctly versus actually knowing the truth. It's different from an actually unblinded study even if participants can "guess" correctly.
In order to understand the difference, you'd have to have a blinded and unblinded study, and compare the results. Then you could understand the difference between a guess with 90% confidence and actually knowing what treatment you received with certainty.
It seems reckless to presume the difference (between blinded and unblinded) is small. The numbers you cite (94.7% and 90% confidence) have nothing to do with the question you're trying to answer.
For example, an important difference may be with respect to expectations. If you're told you're receiving a psychedelic treatment, you may go into the experience with different expectations than if you were unsure about what treatment you were getting.