I have test on Ubuntu 20.04, 22.04, 23.04, 24.04. All of them have the same bug on my machine.
And I also have tested on the HDMI and Display port on the motherboard side.
And when I switch to LightDM, the monitor can turn off but the lock screen shortcut won't work and I don't like LightDM very much.
My machine is i3-13700K on a Z790-PLUS motherboard, and no GPU.
This bug is annoy.
I have test on Ubuntu 20.04, 22.04, 23.04, 24.04. All of them have the same bug on my machine.
And I also have tested on the HDMI and Display port on the motherboard side.
And when I switch to LightDM, the monitor can turn off but the lock screen shortcut won't work and I don't like LightDM very much.
My machine is i3-13700K on a Z790-PLUS motherboard, and no GPU.