This is not a topic of your love or hate of Alexa. Just communicating with others who use Alexa in their HE automations.
A light came on last night, and it was ungodly annoying. I could see it from the bed so it obviously woke me.
Digging this AM I found the trigger. A new feature of Alexa. (well. technically a change).
In my environment I now have a Lighting Features in the device settings page on the discovered devices.
This 'Away Lighting', I did not enable. it just appeared. Thats fine. But the default is to add NEWLY discovered devices to it. Thats bad.
As I add (swap technically) old devices that I left behind with replacements, a new light switch automatically added itself to this Away Lighting rule. which generates random lighting routines when Alexa is in Away Mode.
The solution is an on/off checkbox in Alexa app for 'add newly discovered devices'. It's default is on. Solve by unchecking.
A second item Devs and users need to watch for - is I'm part of Beta and no doubt the whole world is. Amazon has released for testing Alexa +. My first stumble was multiple commands. So be aware a new wave of issues may be on the horizon.