Instacart Full-Stack Engineer Interview Experience — A 90-Minute AI-Assisted OA and Next-Day Rejection

I took the Instacart Full-Stack Engineer Assessment on Codesignal on September, after referred by an employee of the company. It was similar to what posted in the platform here:
5 questions, 90 minutes. Two questions involved chatting with the AI to get the requirements. Two AI assisted Coding with Claude Code, and One bug fixing question withouot AI. There was a tab that showed the live results of your implementation of the web app.
The first coding question is simpler and relatively shorter, which is adding search and filtering functionalities. In my chat with AI, she asked for my preferred tech stack and I chose Python (FastAPI), React among options. Maybe it's possible to choose and solve it in another tech stacks too.
For the bug fixing, search "metrics" and find the related file. The query for filtering of the items should move to the next lines so filtering works properly.
The second part of chat with AI and implementation was much longer, with many requirements. It was about adding a notification service, with in-app notification for availability and due date reminder with lots of edge cases (idempotency, async, etc). Here I selected Celery and Redis as my tech stack.
Overall, the time is really limited, and hard to review all the generated code by AI. I thought I did it okay after getting a score of +650/1000 and I thought I would go to the next round, but next day I got a rejection email.