Instacart Software Engineer, L3/L4 interview questions

In theory, the interview process looked like this: 1) 4 LeetCode-style questions, unproctored (70 minutes) 2) Recruiter Screening (30 minutes) 3) Virtual Onsite - 2 coding challenges, proctored (60 minutes each) - Behavioural interview (45 minutes) - Guided systems design (60 minutes) 4) Frontend guided systems design (60 minutes) In practice, I went through 2+ months of their "interview process". It started with a LeetCode-style technical challenge, followed by a recruiter call. Throughout the process (until the very end), the recruiter seemed quite kind and communicative. After the recruiter call, I did 4 hours of interviews for the virtual onsite across 2 days. These felt positive. I heard back a week later that they wanted to add another frontend systems design interview to the process because they had not given me a challenge that was relevant to the role. At this point, we are 6 interviews in (4 technical, 1 recruiter, 1 behavioural). I reluctantly agreed to the 7th interview. They scheduled it and cancelled it 4 separate times, quoting staff availability and training issues. One of the times, they gave me 2 hours notice. Every single time, I would practice and prepare for a few hours beforehand. After over a month of rescheduling, I finally had the interview. It was the best interview performance I had in my estimation. I sent a follow-up email the next day to thank the interviewer and was told they would be in touch shortly with the next steps. A week passed. I emailed again and was met with an immediate auto-reply from the recruiter. She was no longer with the company. I emailed the head of recruiting listed in her autoreply and got two sentences back, the last of which said, "Your experience does not match our requirements". I have since been ghosted while asking for a more in-depth explanation and a copy of my signed NDA. I do not know how to express how negative this experience was.