By default, Cortex sends anonymous usage data to Cortex Labs.
If telemetry is enabled, events and errors are collected. Each time you run a command an event will be sent with a randomly generated unique CLI ID and the name of the command. For example, if you run cortex deploy, Cortex Labs will receive an event of the structure {id: 1234, command: "deploy"}. In addition, the operator sends heartbeats that include cluster metrics like the types of instances running in your cluster.
Telemetry helps us make Cortex better. For example, we discovered that people are running cortex delete more times than we expected and realized that our documentation doesn't explain clearly that cortex deploy is declarative and can be run consecutively without deleting APIs.
If you'd like to disable telemetry, modify your ~/.cortex/cli.yaml file (or create it if it doesn't exist) and add telemetry: false.