BTW anyone: You want to install Caddy from your distro, but still want to disable (or enable) telemetry? Not possible., at least when the Caddy devs do not decide otherwise.
They insist on a compile time configuration. So if you only have access to run-time stuff or don’t want to mess with binaries, without automatic upgrades, you have no way of disabling sending data to Caddy from your own web server.