[Silhouette]

Since when does the telemetry even send out any contents of any files?

Since pretty much forever? At the very least, many programs with built-in telemetry have included things like memory dumps of key areas at the time of a crash, which could include data the user was working on at the time.

More seriously, I invite you to read Microsoft's extensive privacy policies and try to satisfy yourself that they don't grant themselves the right to upload your code. They are sufficiently nebulous and ambiguous that they could probably be interpreted that way.