Dear Maintainer,

The power save in trixie is so aggressive that it shuts down modern monitors completely (tested on Iiyama, Kurui and Samsung). As a result, screen lock shuts off the monitor and xfce4 tries to run a "connect new monitor" dialogue on a blankblack screen (the monitor comes up from a power off/disconnect state). This makes any desktop with xfce4 and trixie unusable - if you get the monitor into this state you can recover only by restarting lightdm from a text console.

There is a workaround. If there is a default profile created in the xfce monitor settings, xfce4 can load that and you get a working system.