Maybe, maybe not:

1. It looks like ETW is enabled by default since Vista.

2. The code deletes the username due to "PII issues," suggesting that something is being sent back (line 295)

3. An oblique reference to a 5% sampling rate (line 284) suggests you may not be able to tell what it's sending based on network monitoring.

Apparently they are considering stopping collecting the list of processes due to "community consternation" but have not yet: https://github.com/microsoft/terminal/issues/6103

They could at least document what they collect so we aren't left guessing. https://github.com/MicrosoftDocs/terminal/issues/139

All that said, it is legitimately great that the source code and these issues are available publicly.