High battery usage (no wifi no apps no wireless)?

I’ve noticed that I lose about 20% battery each hour while my phone is unattended and offline. I check the battery settings and find that no apps are running.

The phone is rooted, and I’m wondering what kind of cleanup I can do in terms of searching for viruses and botnets and doing some kind of deeper inspection of battery usage?

Samsung galaxy s10+

–UPDATE–

I’d like to start looking for botnet that would survive a successful re-rom: any methods of doing so would be greatly appreciated. I’ve been receiving "unauthorized network" errors while in airplane mode. This is an intermittent issue. I am trying to find a forum or a community where issues like this can be discussed. I’ve taken comprehensive logs at various suspicious cross periods. One of four nights I receive these issues, for example. I vigilantly reproduce steps to be sure that each night the conditions of the phone are the same: turn all apps off, restart the phone, put it into airplane mode, turn the screen off, leave it unplugged.