Phone screen 1: 45 min call with a manager at FB: behavioral questions.
Phone screen 2: posted here https://leetcode.com/discuss/interview-question/560984/Facebook-or-Phone-or-Product-of-Array-Except-Self-and-Divide-Integers .

Virtual Onsite - NDA: cannot reveal exact questions; most are from FB list, with slight modifications.
All rounds are 45 min, with a break only between 2nd and 3d ones.

Round 1: Behavioral + LC easy (strings addition).
Round 2: Coding: LC medium (nested data structures) + LC hard (string/parenthesis problems variation)
45 min break;
Round 3: Coding: non-LC, I'd say "hard side of medium" (sorting huge amount of data).
Round 4: System Design (Gr...g medium).

Round 1 & 2 went great. On round 3 I couldn't understand for a while what exactly interviewer wanted me to implement - it is possible we ran out of time for the second question.
For Sys Design I used screen share (instead of proposed Google Drawing) and drawing on my touch-screen laptop.

Even though I cannot tell the exact questions, I hope this will be useful for someone looking to interview with FB.