Disabling Suspend on Debian 12

https://unix.stackexchange.com/questions/361214/disable-gdm-suspend-on-lock-screen/736305#736305

That’s because of the idle-delay setting. To change it you’ll have to alter the corresponding dconf key (and do that as the gdm user):

1. switch to a VT (e.g. Ctrl+Alt+F3), login as root and run:su - gdm -s /bin/sh to switch user to gdm.
2. then run:export $(dbus-launch) and set idle delay to 0 (which translates to never):GSETTINGS_BACKEND=dconf gsettings set org.gnome.desktop.session idle-delay 0 run exit or hit Ctrl+D to return to root account.
3. reboot your machine or restart the display manager:systemctl restart gdm

su - gdm -s /bin/sh
export $(dbus-launch)
GSETTINGS_BACKEND=dconf gsettings set org.gnome.desktop.session idle-delay 0
systemctl restart gdm

vi /etc/gdm3/greeter.dconf-defaults

sleep-inactive-ac-timeout=0
sleep-inactive-ac-type='blank'

sudo systemctl reload gdm; sudo systemctl reload gdm3