https://www.jwz.org/xscreensaver/faq.html#typeahead
This is an inevitable consequence of the new security model introduced in XScreenSaver 6.00. The old behavior will not be returning, so get used to clicking the mouse or tapping "Shift" before you start typing your password. Just typing blindly had always been bad opsec anyway: if the screen was only blanked but not locked, you probably would have accidentally typed part of your password into another window.
