simpledrm / lightdm race condition leads to black screen

[LightningW9]

Since the upgrade from Xubuntu 23.10 to 24.04 there is a race condition with lightdm/drm gpu driver on boot leading to blank screen. Temporary workaround is to disable splash in grub.

Logs:
Log of failed boot to black screen: https://pastebin.com/6SGEvAtf
Log of passed boot (splash disabled): https://pastebin.com/q5wLFW0Q

Launchpad bug:
https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/2063983

Same issue with SDDM:
https://bugs.launchpad.net/ubuntu/+source/sddm/+bug/2063143
sddm/sddm#1917

Similar GDM issue that was resolved:
https://gitlab.gnome.org/GNOME/mutter/-/issues/2909