A handful of SDN-shown swimming pools nevertheless have an “operator” permission. Of these, two belong to very previous, now-unused versions of Tornado Cash. The remaining pools possibly have more recent, immutable versions, or have been used so small they ended up most likely ignored during the Might 2020 ultimate update. https://smithbrauerblog.com/how-tornado-cash-enhances-privacy-for-ethereum-and-bnb-transactions/