Yay, your ISP is monitoring whether or not you're home based on Wi-Fi signals. That info won't leak, no siree! We can't abuse that in ANY way....
"...WiFi Motion can monitor activity in your home and send you notifications, similar to a standalone motion sensor. It works by detecting disruptions in the Wi-Fi signal between the Xfinity gateway and any Wi-Fi-connected device, giving you some insight into what’s happening in your home without buying additional hardware...."
https://www.theverge.com/news/981381/comcast-xfinity-shield-wifi-motion-sensing