Proofpoint Was Not Told At All interview questions

The person calling told me this was going to be an introductory call to tell me about the position. They quickly descended into systems design, oops questions without any prior indication this was going to be a tech interview. Till the end, I was not told what the position was. Towards the end, the interviewer expresses that the interview went downhill and none of the questions were answered right. Which was odd to me because I know that was not the case, even if they weren’t happy with the answers. They proceed to state they’re disappointed with me. Extremely odd way of interviewing with no prior notice, no clear description of the position and then disparaging the prospective employee