They asked a lot of really senior-level questions about B-trees. Since I tend to use hashes instead of B-trees for my data structures, I was caught completely flat footed.

To interview for Facebook, study B-trees like crazy (no, the recruiters did not warn me about this).

Also, after the interview, the recruiters at Facebook I was in contact with completely ghosted me. Very rude.

A recruiter explicitly told me to study trees and related algorithms and even offered an FB study guide. However this happened after I told them I didn’t do game show style interviews. YMMV.