Opt-in telemetry, as well as unspecified telemetry while phoning home for license checks. I gather from memory that IDEs based on the IntelliJ platform scour the local network in search for other local network-connected machines running instances of their IDEs - e.g. in order to detect forbidden duplication of licenses. It is not apparently clear what details are(n't) transmitted back to the mothership.

This example requires a finer-grained analysis than the broadly chosen "opt-in" and "opt-out" categories to describe telemetry collection, and I wish for this information initiative to improve in clarity and thoroughness (e.g. does VSCode also scour the local network?).

Addendum: Thanks for asking for clarification. The grandparent comment could've been ambiguous in intent.

I’ll add anything worth adding, regardless if it has telemetry or not. The tools on the site just the ones I tested!