Just to tell that solving my Asus zenbook Xubuntu standby issue (black screen and no standby) with this grub modification:
quiet splash i915.enable_psr=0 mem_sleep_default=deep usbcore.autosuspend=-1
as discribed here (Random crash when standby (asus zenbook) - #2 by amosse05)
also solved my battery drain issue on standby, before it drain more than 15% in one night. Now it is 3%