Standard interview track: recruiter, hiring manager, take-home assignment, panel interview. Four interviews were scheduled, two technical on the first day and two culture on the second day. I was told that I would only take the second day interviews if I passed the first days, but figured I couldn't bomb that bad.
The first interview was an hour to go over the take home assignment, in the form of a github PR, and then add a new feature to the assignment in paired programming (saying it was ok if we weren't able to finish within the hour). The interviewers complimented my thorough PR and we successfully completed the entire task with time for questions at the end. Before starting I ran through my approach on how I would complete the task, which worked as expected.
The second interview was a little weirder. I was just given one sentence (see interview "question" below, a direct copy and paste of what I was given) followed by an awkward few seconds of silence. I was told that this is usually a whiteboard exercise, but since this was a remote interview they gave me a Google doc to take notes on instead (instead of, you know, the many online whiteboarding applications.) Because the "question" was so vague I asked a lot of questions and made a few false assumptions, which were immediately corrected and the discussion continued, but otherwise I felt like the interview went well.
No more than an hour later I got a rejection. I was offered a call for feedback, which I was happy to take. I figured the issue was going to be with the architecture interview, but I couldn't understand how it went so bad that I wasn't able to take the culture fit interviews (especially given how quite literally everyone said good culture fit was the number one thing they looked for in a new hire.) The feedback I got was like it was from another reality. They said I wasn't prepared for the PR discussion (because I took 30 seconds to reorient myself with it?) got stuck during the paired programming (no??? was it because we discussed whether a poorly worded function meant one thing or another?) that I didn't ask clarifying questions during the architecture discussion (literally impossible not to) and didn't think high level enough and got too concerned with a discussion on network code (interviewers gave literally zero indication of what they were looking for. I'm an app developer, I talked about the architecture of the app. Not the architecture of the backend server protocol.)
After receiving feedback, I tried to voice my concerns, but was cut off and hung up on.
I've been in many interviews over my career and I can honestly say I never came away feeling like I had been backstabbed before. If there is one bright side to all of this, they saved me a future of having to work with these people. There are multiple reviews for iOS roles for this company within the past few years. All negative, all true, save yourself the effort.