Application
I got contacted by a sourcer if I'd be interested in a position at Facebook. I asked for a few weeks for prepration.

Phone screen(45 min)
The interviewer jumped right into it. He asked 2 questions and I solved all of them.
Note - They don't expect the candidate to execute the code on the platform, but rather explain how the code works.

Onsite(4 rounds)
I prepared mostly for coding questions. Apart from 2 coding rounds, there was one system design and another behavioral round. Due to NDA can't disclose the questions, but most of them were from FB tagged questions on LC. Premium subscrition is really worth it. Even the recruiter suggested LC :).
Each coding round had 2 questions. They asked questions on Linked List, Tree, Stack and Backtracking.
In the first round, although the questions seemed easy/medium types, but I quickly realized that they are not looking for a brute force solution. So instead of jumping into the solution, I spent time in different approaches and coded the approach after agreeing that this is an acceptable approach. This round went well.

In the next round, I missed some corner case in the first question. For second question, the interviewer gave feedback that the solution will work but is not optimal for compute complexity. The decision tree in my solution was having n-ary whereas they expected it binary tree. I changed the approach and coded it quickly. Most of the time was spent in discussion on approaches.

Result
Considering that I had not failed to identify the optimal approach and the solutions I gave were not completely off, I was optimistic about the result that atleast they will offer but may be with a lower level.
I got a no on behavioral and system design rounds. 1st coding round was ok but 2nd was not at par.
Final thoughts
Apart from coding, the other rounds are equally important to 'crack'. The answers are expected in a specific format. In the hingsight, If I had prepared for non-coding rounds as well, I would had a better chance of getting an offer.
In terms of interview experience, the interviewers were very well prepared for the coding question. They were constantly communicating and giving feedback and it felt like we're working in a team to solve the problems! There were no brain teasers, they are looking for speed. If I were to advice one thing, then that would be to practice most frequently asked medium LC questions and aim for most optimal solution in 15 minutes.