What is iCloud DNS Bypass
I just connected my MacBook Pro WiFi to my iPhone personal hotspot, and an app window appeared telling me I was now using iCloud DNS Bypass Server ... Little Snitch showed it wanting to connect to captiveagent, Captive Network Assistant, and identityservicesd.
Google shows iclouddnsbypass.com as a site which may damage your computer.
FWIW my iPhone has Find My iPhone enabled and it was purchased new, unlocked from Apple Store by me.
I see this issue was posted in 2016 and supposedly router-related.
https://discussions.apple.com/thread/7409479