Display turns on again while going into hibernation
Before going into hibernation, the screen turns off - but after a few seconds, it turns on for a few seconds again, until the laptop actually turns off. I'm not sure where exactly this bug comes from, but as it happens independently of the used display server, I assume the problem is in the kernel.
This is on a HP Envy with a 4700U. Someone in the kde bugtracker has the same issue with a 4500U, too: https://bugs.kde.org/show_bug.cgi?id=454626