I was running KDE Neon on ThinkBook 15 G2 and had deep sleep working after adding mem_sleep_default=deep to GRUB_CMDLINE. It worked for a while until it didn’t. I didn’t do anything other than running regulat updates. Since couple weeks back, when going to sleep, it shows BIOS Recovery progress bar or something and restarts.
I switched to Debian and the behavior is the same. S2 sleep is next to useless as it drains something like 10% battery / hour, and the lap top is warm to touch.
No, hibernation saves state to disk, and turns the computer off, drawing no power. Deep sleep is what was for me just sleep until recently: it uses power to keep data in ram, so it’s faster to wake up than hibernation. The amount of power used is really small, so unless you don’t use your lap top for a couple of days, it won’t deplete the battery. New hardware has this new “S2 Idle” state, that is basically an “On” state minus the screen and it’s OS’s job to try to use as little power as possible usually by telling each and every device to chill as much as possible (this is my understanding, but don’t quote me on this). On Windows, with the first party device drivers, this sorta works OK + OS drops to deep sleep or hibernation depending on battery or something.