I have another laptop that works perfectly with the same external
screen. Also Bookworm, both up to date, same configurations for
Plymouth, initramfs and grub. I checked the initramfs content and
couldn't detect a difference related to the display.
The laptop with the issue is a Thinkpad X1 gen6, with a 2560x1440
display. The laptop that works fine is a Dell Latitude 7490, 1920x1080
screen.
A difference in behavior is that the Latitude shows the same thing on
both screens: I can see the LUKS entry field and my input on the
external screen too.
On the X1 however, the external screen has a fixed image with no input
field. The laptop screen is truncated so I can't see the input field,
but I assume it's present (I can enter the LUKS password just fine). So
it seems Plymouth displays different things on both screens. On Bullseye
it didn't behave this way: both screen showed the same thing on the X1
too, with no truncation on the laptop screen.
Suggestions on how to troubleshoot this welcomed ;)
