Meta Senior Software Engineer interview questions

Call with recruiter, tech screen with a couple random leetcode mediums not in the meta list, then some more typical medium meta list leetcodes with slight differences in coding rounds and a couple of system designs one is easier and one difficult and a behavior round.

I interviewed for a specialist engineer role. Onsite consisted of two coding, then one behavioral, then two system design. The first system design round was great, had a chance to meet some very experienced people in my field and talk about interesting concepts. However, the second system design was not great. This one was specifically out of domain for me, and asked how to design something completely unrelated to the job's position. Keep in mind this is for a specialist role and not a generic software engineer role. The interviewer for this round was also a specialist and didn't seem to know the material either, so I'm really not sure what was the point. Received a rejection a few days later.