The interview format for Software Engineers at FAANG (and similar companies that follow the same structure) comprise of a System Design Interview portion. From recent interview experience, I learnt that for SDET roles, they sometimes have a counterpart module where they ask the interviewee to design a test plan/ strategy for a similar system.
For example - what will be your test strategy to test a photo-sharing app (like Instagram)? Since the position is for SDET/ Test Automation Engineer - you are likely to provide your automation test strategy along with Exploratory Testing.
The initial question will be very abstract, and you are expected to drive the conversation to understand the requirements and then provide your best possible answer.
Are there any templates/ tutorials to help answer these types of questions, as I flunked this round completely. The feedback provided to me was - 'concerns about test coverage', even though my coding & behavioral rounds went fine.