Default "Blank Screen" screensaver tricks some users into thinking they have a power management problem.
New users believe power management has kicked in, then go about disabling it. Only to find their screen still goes blank. "Blank Screen" should not be the default screensaver in Xfce. A better option might be something like "Floating Xfce" which is an obvious screensaver.
I've seen two instances in the past month with this issue (links below).
https://old.reddit.com/r/xfce/comments/knub0a/xubuntu_making_screen_black_on_idle_even_though/ghmnh5w/
https://old.reddit.com/r/xfce/comments/llpui9/is_there_a_way_to_completely_deactivate_power/gntd67h/