I advanced to a final round interview which got off to a rocky start due to technical difficulties. The interview itself was fine, but the interviewers continued pressing on questions after I had already indicated I wasn't sure or didn't know the answer, which felt unnecessary and uncomfortable.
Most notably, a second interviewer was brought into the call without any introduction or advance notice, and remained off camera throughout. That lack of transparency left a poor impression of how the company conducts its hiring process.