I have already disabled in windows things like inactivity detection, hibernation, etc.
It was a very bad idea to disable inactivity detection and especially hibernation. I believe that the sleep mode on Chuwi tablets does not work as a sleep mode itself. Of course, by pressing the Power button or closing the lid, we can see that the screen goes blank. But this is not a sleep mode. This is turning off the screen and locking the login and nothing else.
It's easy to see that the tablet goes into hibernation instead of deep sleep. We have no any deep sleep after 4 minutes of inactivity with default power settings. Any activity in the time interval of up to 30 minutes leads to turning on the screen. After half an hour of inactivity, you can to turn the tablet on and to boot Windows from hibernation mode only, but do not wake it up from sleep mode. Thus, the tablet goes into hibernation instead of deep sleep always. And this happens despite the fact that according to the settings it should not go into hibernation ever.
What happens to a device that does not support sleep mode and in which inactivity detection and hibernation are disabled? Can you answer this rhetorical question?
it happens without a single device connected.
I have no device on my Hi12 Z8350 too, but the problem still exists.
I'm afraid that you both are mistaken and do not fully understand the meaning of the connected devices in the phrase. You should look at this concept much wider. Do not forget that there are Bluetooth devices and LAN with network access and so on.
Besides there are tasks in Windows, software and including all sorts of malicious programs, which also may not allow the device to go to sleep. In our case, to go to hibernation.
About the help from Chuwi. You should separate flies from cutlets first. As the proverb says, the rescue of drowning people is a matter for the drowning.