M1 MBP 16" won't sleep for long

I have System Preferences to have the unit sleep after a period of inactivity. It doesn't. I have wake for Network Access disabled. I also manually put it to sleep and the screens turn off, for a time, then they go back on again and stay on all night. I talked to Apple Support by chat and think I only got a Bot, but it said that "Thanks for sharing. For Mac with silicon the sleep mode won't be able to get the display to stay off. That is how these model Macs are made. It is better if you set a time for the Mac to shut down whenever you are through are after some time of inactivity."

Is this true that M1 Mac's won't sleep?