Heiman smokedetector turn off by device

I’ve installed a Heiman smokedetector in last oktober, and from that period my Homey app showed regular (18 time) a message “smoke detector turn off by Heiman”.
I noteced sometime a single sound, not a alarm. What is the cause of this message?

I have only one flow with an alarm pushmessage by alarm, the flow was not activated.

I think you’d better create an issue on Github (support links are often present at the bottom of app pages).
In this case there’s a link to the Github source