I had applied through a referral, hence OA was skipped for me. I have 4.5 YOE, so was pushing the recruiter for SMTS role since the beginning, hence the need for an extra round.

Round 1 (DSA) - Taken by SMTS (SDE-3)
This round had 2 questions, expectations being to first discuss the approach with the interviewer and once he was satisfied with approach, would move to coding and then to test cases execution.

1. Don't remember the exact question on this and i also couldnt find a similar one yet anywhere but i will try to give a somewhat idea here. I was given a binary tree and had to modify the tree where the leaf node values would be added to the value of their ancestors, and this behaviour would continue bottom to up for all children and their ancestors and once we complete the right subtree with modification, the value would be forwarded to left subtree from root to leaf. I took a lot of time on this and couldn't come up with a end to end soultion. My solution where covering couple of tests and missing on a couple.

Post this i realised i am not going anywhere with this question, so asked interviewer if we can move to second question and come back to this. He said ok.

2. Similar to - https://leetcode.com/problems/pacific-atlantic-water-flow/
   Quickly gave a dfs based approach, the interviewer was satisfied with the approach, coded the solution and the test cases he ran passed successfuly. In the end he asked why did i used dfs over bfs and how does that help. I gave the answer and we ended the interview there with me asking a question about his work.

Round 2 (LLD) - Taken by LMTS (Lead engineer)

1. I was asked to design a message queue (not put in this term by the interviewer). I had to figure out that it was a message queue towards which he wanted to take the discussion. Went through this round pretty smoothly. He was satisfied with the implementation, approach and design decisions taken. In the end he also asked about how to message queues fit in a system overall and how do they help etc.. . Finally i asked a question about the company and we ended the interview.

Round 3 (System Design) - Taken by LMTS
Interviewer asked to design the HLD for the Flight Booking System. I started with a detailed design discussion, gathering all his specific requirements. What all services would be needed. He was not much considered about the external system that we will use to check flight seats etc and availability. He was much more considered about how our booking service would be designed, how would we manage synchronization problems. He then asked about the payment service, should we use a third party service here or our own. Overall this round went pretty smooth again. I asked a question about his work and we ended the interview

Round 4 (Managerial) - Taken by EM
This was purely managerial. He only wanted to check my team fit/cultural fit, the kind of work i have done till now and how to i fit into his teams overall picture. Sailed thorugh this round smoothly.

After this round my interview loop was supposed to be completed, but since i was pushing for SMTS role and my round 1 didnt go pretty well, they scheduled another problem solving round (the reason for scheduling this round i was not aware of at that time and hence got nervous to some extent thinking that what have i messed up)

Round 5 (DSA) - Taken by PMTS
This was purely on problem solving, no introduction given by the interviewer, neither did he ask anything. Joined the call and started giving dsa questions to me.

He gave me 4 questions based on DSA, out of which for 1 he asked only for psuedocode and for 3 he wanted completely running code with all test cases passing.

1. Topological sort based question - Wanted running code. I coded it up and it passed all the test cases and we moved to next question
2. Meeting rooms - Wanted only psuedo code, i wrote the psuedo code and he was satisfied
3. Top K frequent elements - Gave heap based approach, he wanted me to optimise it, used bucket sort. He asked for code and i wrote the bucket sort code with all test cases passing.
4. A question based on sliding window - He gave the question in the form of a puzzle, i had to deduce the pattern myself and then eventually come up with a solution. I explained him the solution correctly, but messed up a bit in the code and due to time running out, he didnt give me time to debug and fix the code.

Post this he asked a few questions on scalability and design terminologies which i answered and we ended the interview with it.

Post this i got a call from recruiter and i was offered the MTS role.
Leetcode community has been very helpful in this preparation journey and i thought of giving back to community. This is my first post here so please ignore if any hiccups are there in this :)

Hope this is helpful !