Abnormal AI interview questions

I interviewed in Spring 2024 for a Senior Software Engineer position. The recruiter seemed nice, and I enjoyed speaking with everyone in the interviews. I did two recruiter chats, two Hiring Manager screens, a Coding screen, and two 2-hour panels. It was alluded to that there may be another top-grading interview after the panels, but I was rejected (without feedback) after the panel interviews. I was left confused without feedback in the rejection. All interviewers told me I did well, and considering the recruiter's rejection email said "please let me know if you have any questions" I requested some feedback from the recruiter to improve my interviewing via email, and was completely ignored. Pretty discouraging and disappointing to receive no reason for rejection after what felt like only positive feedback after about 7 interviews/chats, not a great way to treat candidates. I appreciate they may not be able to give feedback for liability reasons, but say that and don't mock people with the illusion that you'll answer questions. The technical interviews seemed to focus on the specific technologies that they use, and without proper heads-up or warning of that in terms of preparation notes. The system design wasn't really a traditional system design and they ended up grilling me on SPARK - it seems like they have inexperienced interviewers on some teams.