From what I could find on the internet, Flipkart’s machine coding round, especially for SDE-4, is usually a real-world app design problem that tests your system thinking and code structure. One common example is designing a ride-sharing system where you build features like user onboarding, ride offering, selection strategy, and reporting. You’ll typically get 90 minutes to code and 30 minutes to walk through your solution. Disclaimer: I've never gone through this loop myself so take this with a grain of salt!

+1 to this. I’d also suggest brushing up on object-oriented design patterns and practicing a few mini-apps like Splitwise or Snake & Ladder. Those come up a lot. This Medium post helped me prep: https://medium.com/@anmol15554/flipkart-interview-experience-for-sde-2-9b7fbfadbdf1