I applied through LinkedIn and got the call from Recruiter. The first round was OA. Below is my interview experience with Amazon.
OA :

1. LC Medium (String Manipulation)
2. LC Medium(String Manipulation)

I received a call from recruiter after 2 working days and interview was scheduled. All the rounds were virtual.

DS & Algo

Day 1
Round 1 :

1. LC Medium(BFS) :Wrote the optimal code and covered all the edge cases.
2. LC Medium(DFS): Approach, optimal code, time and space analysis was expected. Wrote the code upto the expectations.

Round 2 :

1. LC Hard(Arrays) : After series of discussions and clarifications, was able to come up with the optimal solution. I was asked to change the code 3 times, to optimize it.
2. LC Hard(LL) : I had practiced this question before the interview, solved it within the stipulated time and covered all the edge cases.

Overall, Day 1 was fruitful and I was optimistic and confidence level high.

Next rounds were scheduled for next business day.

Day 2

Round 3
System Design :
Difficulty Level : Medium -> Hard.
Only one question.
Expectations:

1. Gather the requirements.
2. Set the scope.
3. HLD
4. Sizing
5. Schema
6. LLD
7. Happy Path
8. Failure scenarios
9. Scaling
10. Database choices and write few queries.

This round was fairly good, and went on upto 80 mins. I felt I covered most of the scenarios. And I was confident.

Got the call in the evening for the next round, scheduled for next day.

Day 3
D-Day, the day where everything that could go wrong went wrong.

Round 4
System Design + OOAD
LC Hard :
The moment I heard the problem everything went blank. I had no idea about the system. Entire thought process went for a toss. He expected me to come with design and class diagram. I struggled to gather the requirements as I did not know what all could be the components. I tried to get it clarified with interviewer, but the dude was in no mood to help.

Finally, after 45-50 minutes of struggle, I told him I have zero clue about the system.
He then just asked me standard question "Do you have any questions ?" , I was blank, I could see my dream plumetting right in front of my eyes. Just asked him a normal question and hung up post his response.

Got the call from recruiter the next day, that feedback was not good. So, they are not taking my candidature ahead.

Important Lessons:
You cannot take any round with Amazon for granted. Don't be complacent. DS and Algo is just the begining, SD and OOAD are different beasts and you must put the same amount of energy and effort on these topics too.

All the best. Love and Luck!