read -s in pdksh does nearly the opposite, saving the string to your history file! See https://man.openbsd.org/ksh#read pdksh is the system shell on OpenBSD, among others, and I just confirmed this is indeed what it does in OpenBSD.

EDIT: FWIW, ksh93 also behaves like pdksh (inherited ksh88 feature?), while zsh behaves like bash. read -s was added to bash 2.04 (2000) and zsh 4.1.1 (2003, committed 2002), both long after the flag was used in ksh--at least as early as the initial pdksh commit to OpenBSD in 1996.

Yeah, I came to Linux from BSD and still have some ksh and csh muscle memory from The Before Time