Current Status : 9 YoE, working in another IB.
This process started in February and I got the rejection mail in June after multiple follow-ups.
I was very invested in the tech org that I was applying for, I felt I would be a very good fit and my thoughts were actually validated throughtout the process as I talked to some of their interviewers.

Round 1 - Exploratory Call : Had a call with a Senior VP from that technology area. It was a generic discussion about what I have worked on, my roles and responsibilities etc. He gave an overview of their technology area and the position they're hiring for.

Round 2 - DSA Coderpad : This was the coding screen round. The interviewer was very level headed. She started with saying that we will target to complete two questions in one hour. I was able to code both questions and the test cases passed too. The interviewer was very good in terms of dicussions, approach, test cases, everything. Probably the best interviewer of my entire experience with GS this time.
First question was a sliding window problem with strings. Can't seem to recall the exact question, but it was a LC medium.
Second question was about finding median of two sorted arrays.

After clearing coderpad screen, recruiter called to let me know that I will have 3 technical rounds followed by a HM round and that each round is elimination round. I asked if he can clearly define beforehand what type of round it will be DSA or LLD or HLD but the recruiter said that it's not known and the interviewers can ask anything. This was actually weird and does not line up with my experince of other big tech companies, kind of the start of problems for me.

Round 3 - Problem Solving : I ofcourse had no clue what to prepare for this. So i just continued with my general DSA and System Design studies without focusing on GS too much. There were 2 interviewers in this round.

First interviewer asked me a question about scheduling jobs to optimize maximum completion based on time take by each job and priority of each job. I asked a bunch of follow up questions and some examples, but somehow we did not communicate all that well. She was not able to give me any good examples of input and output either. I anyways proceeded to attempt a solution based on whatever I could understand. I probably did not give the answer she was looking for but I did give some sort of a solution that would work. She also changed the scope of the question in between, not sure if it was to help me or help her or help both, but it ended up helping neither. I still did not get a sample example to work with and I don't fully understand the question, to this day.

Second Interviewr was the same Senior VP who I had the exploratory call with, a sensible guy. He asked me about a recommendation system where the top x movies need to be recommened based off the prior rated movies. I was able to come up with a solution, he discussed and had a few follow up questions and was overall pleased with the answer.
To this person, I again asked that it would help to know for further interviews if they would be based on SD or DSA but he just said that recruiter might be able to inform me on this.

Round 4 - Design : Again I had no clue going into this interview what to expect. This was taken by two junior folks; an analyst and an associate. The interview started late because the associate thought I might not be joining the interview since my recuiter was out of office and somebody else was trying to reach me, whose call I could not pick but had messaged them informing that I'd be available, hence he simply did not join and the analyst kept waiting for him, approx. 10 min. wasted here.

The analyst asked me a LLD question about designing a stock exchange. I was able to answer and talked through a few scenarios.
He had concurrency specific follow-ups which also I was able to answer.
At this point I got disconnected for 2 minutes due to power outage. So again, a bit of time wasted.

The associate asked me to design the stories feature on social media apps. I clarified the system requirements, fucntional and non-functional. He did not provide much input here. I started talking about the high level system interactions and the very basic APIs that are needed. I was getting into how the data will be stored when he interrupted me and said he wants to know how the systems will communicate. I again took him through various options and their trade off like HTTP calls, Websocket, Push vs long poll etc. He seemed dissatisfied and kept interrupting me through this, he was probably looking for a specific buzzword which I was not saying. He then asked me about data storage, I talked a little about the various options we can use in this scenario, the data model etc. and then he again interrupted me and went back to the system communication part. The discussion was not very constructive, the way he was asking me questions was less of a discussion and more of a challenge like can I even do this, do I even know this, an argumentative tone basically. I kept my cool and answered everything he asked, suggested alternatives etc.

For this interview I found out from my sourcer (not the recruiter, GS recruiters aren't very helpful/candid) that in my previous round the feedback is positive for LLD, API design, DB etc but negative for system design, which is funny if you think about it. I designed the entire system, including APIs, storage, communication protocol, so what does it mean when you say not good in system design? This is what a system comprises of - data and ways for that data to travel thorugh the system i.e. APIs, sync or async! She told me that for the next interview one person would be outside of the tech group that I'm interviewing for and that I should expect heavy grilling there.

Round 5 - Grill : The interviewer from same tech org asked me about Rate Limiter design. I took him through the entire system design, API design, data structure design. He asked a few follow up questions, but not too much. He was pretty much onboard with whatever I was saying. The next interviewer then said he doesn't want to ask a different question but wants to continue with the same question. Now, we really deep dived into the rate limiter. I took him through sample examples, not once, not twice, but thrice, I made sure I explain patiently no matter how many times he asks. He then went over scenarios of concurrency, storage options, temporary vs. permanent storage, complexity of the rate limiting call, how to further improve, thresholds, edge cases, everything. He did make it seem like he is grilling hard but I did not mind, I could see he was a reasonable person and I thoroughly enjoyed this round.

After this I was expecting a HM round to be scheduled, my interviews had been good, my conversation with the interviewers were also good, I was very invested in the specific org and the position as well, but the recruiter did not come back with any updates.
I called and followed up with both the sourcer and the recruiter, but no updates from them.
Finally I got a rejection after 3 weeks saying that I'm not suitable for the profile I applied for.
I hope they find/found a suitable candidate and I hope that candidate never joins them :)

Conclusion : Interviewing well is not enough if some of the interviewers are immature or just get competitive with the candidate because that's the promotion they're vying for; does look like a widespread issue in India though. Same, if interviewer is not able to explain the problem clearly, is not prepared with enough examples and changes the scope of the question in between. Also, not telling whether the next round is DSA or System Design is weird, isn't it?