Recently I've observed the coressh.TunnelHelper service consuming 100 to 200% CPU usage. My Core Tunnel app is not running. When I try to kill or force kill - it won't die. Also trying to "sudo kill -9 1234" (whatever PID), it won't die. I've not seen a service that was "unkillable" on MacOS - that's new to me.
I have to save all my work, close all my apps, and reboot. Then it's gone. For a while. Then eventually starts going nuts again.
I'm running Catalina 10.15.7 with ... I THINK ... Core Tunnel 2.6 - I can't find definitively in the app any version number.