I am a big fan of client side proving and was checking out STWO. I think the marketing people don't get it AT ALL and often mislead 😱

Marketing:
"not only scalability but also privacy—increasing economic freedom by enabling private transactions on Bitcoin and Ethereum at massive scale"
https://starkware.co/blog/s-two-prover/

Dev docs are more honest:
https://zksecurity.github.io/stwo-book/why-stwo.html#:~:text=As%20of%20the%20time%20of,to%20infer%20the%20witness%20values

"As of the time of this writing, Stwo does not provide the "zero-knowledge" feature. "Zero-knowledge" here refers to the fact that the proof should not reveal any additional information other than the validity of the statement, which is not true for Stwo as it reveals to the verifier commitments to its witness values without hiding them by e.g. adding randomness. This reveals some information about the witness values, which may be used in conjunction with other information to infer the witness values."