GOS-user after leaving a secondary profile it will allegedly run in the background draining the battery and possibly compromising privacy. Does GrapheneOS cover it?
From the Features overview:
GrapheneOS also enables support for logging out of user profiles without needing a device manager controlling the device to use this feature. Logging out makes profiles inactive so none of the apps installed in them can run. It also purges the disk encryption keys from memory and hardware registers, putting the user profile back at rest.
Naturally, if pressing "End Session" makes the profile inactive and none of the apps installed in it can run, then it can't run in the background, let alone compromise privacy. So, yes, GrapheneOS covers it!