There is a significant bias in the interview process and I recommend FB look into it. I failed interviews where I felt the interviewers had a predisposed mindset and were trying to validate that through their questions. Two interviews almost felt like a bullying sessions and the interviewers were boorish and openly skeptical of anything I said. I didn't graduate from the top universities or work at the top tier companies these interviewers were from but bring in significant experience that got me the interview. I was very bothering by the attitude of the interviewers and I really didn't want to work with that team.

Got an initial email solicitation from a recruiter which resulted in a phone screen that was great. Then had a phone screen with the hiring manager, which also went really well. Was told that a half-day in-person, with 5 back to back interviews was the next step. At this point I was transferred to my THIRD recruiter and she was quite bad. Kept giving me the wrong information, very limited prep, showed up VERY late to the lunch break portion, etc. After my onsite visit I was told that I needed to return for another 1:1. Ultimately was told I wasn't technical enough for the role so they wouldn't be making an offer. FB was quite transparent about the whole process and gave instant feedback, but unfortunately I simply didn't click with the 2 engineers that I met with. The sessions I had with the TPM folks were all extremely positive however.