k so it seems xscreensaver 6.02+dfsg1-0ubuntu1~20.04.sav1 ignores the "mode: off" setting in ~/.xscreensaver which gets set by the xscreensaver-settings GUI and instead you need to manually change "lock" to "False" to properly inhibit the screensaver
because, no, setting "disable screen saver" does not turn off locking and the checkbox for disabling locking gets disabled when you turn to that mode, which according to https://www.jwz.org/xscreensaver/man2.html should not blank the screen and yet it does
i guess i'll just write bash scripts to easily do that from the terminal whenever i want to watch a movie on discord, yet another workaround in the pile of workarounds that is linux