@nprofile1q... if GNOME Software automatically downloaded and staged some update in the background (which it likes to do, even if automatic updates are off), it won't show either in GS updates page or in dnf update - since it's already downloaded and staged for installation.

On the battery draining - do you see the giant checkbox, saying it will reboot and install updates? You are informed about it, so if you chuck it in the bag, it's your fault. Just type in the FDE password. Or uncheck the box