Microsoft Senior Software Developer interview questions

I was amazed how fast Microsoft have managed to run my hiring process. I have already had another offer from a high value company, before signing there I thought to check my luck with Microsoft. Knowing that, HR called me day after I have submitted my CV, she scheduled a back to back 3 interviews in 4 hours for the following day. The interviews were well organized, I felt very welcome (using Teams- remote interviews with team leaders from Redmond USA). First interview, getting to know me, talk about some technologies I worked with and my thoughts about each and my experience. Second interview, I presented some work I did in the past in the first part and on the second part was asked to design a system in high level (networking, security, proxy, vpn, on-prem and cloud). Third interview coding question, solve an algorithm question in the subject of stacks and queues- felt easy on first read but luckily found a catch in the middle (ended up to be harder then I thought, but still managed to solve it). I got a call the next day letting me know we are moving to an offer. Got the offer letter the same day, salary and benefits were way above my demand. I was given a week to decide.

1 recruiter interview, 1 algorithm question face to face, and site interview with 4 people for 1 hour each. The site interview has 1 behavioral and 3 technical parts. First Question is design a whats up system, second question is transformation of data from legacy system to new system when both of them in live environment.