I'd be very surprised (and impressed) if any interviewer gives honest feedback on the interview, in writing (via the app), esp. in cases where candidate was rejected / didn't receive an offer.
Cos that would have a discrimination lawsuit written all over it. HR and/or Recruiters also never gives candid feedback for the same reason. Because if they do, someone will eventually sue the company for discrimination.
Ex: The most common cookie cutter response for rejection based on ageism is "We really loved you, but unfortunate there wasn't a cultural fit."