I have encountered push notifications with leak sensors. It seems to be a response that is built-in to ‘the system’. There are equivalent responses for some other categories of devices. If you open the mobile app and visit Menu > Notifications > three dot options menu > Notification settings or Menu > settings cog > Notifications (click on the name, not the slider) you will see that there are on/off sliders for all of your devices, and it is the built-in notifications that they are controlling.
I’ve not seen anywhere to specify a default speaker for audio notifications so I can’t see how they can reasonably be a default response. That wouldn’t stop them being an unreasonable response.