possible route..
I had the same issue for a few weeks now, random lights going on at random times.
all credit to @Mherwege who provided a url where you can check exposed devices.
https://community.openhab.org/t/items-randomly-turning-on/135870/15?u=peacemaker
My device was on the list! i had some portforward setup on my router to my RPI.
So disabled these ports again.
I tested this and it does not connect to my device anymore.
Wonder if there is a way to leave a message to those exposed devices to warn them..