Initial interview involved meeting virtually with a developer or two. The first half they selected two data structures and asked me to explain what they were, when/how they're used, etc. The second half of the interview they asked a basic whiteboard question where I had to solve some problem. Before we started they said I could approach the problem in one of two ways: I could have them silently watch the whole time without saying anything until I was done, or we could do it in more of a collaborative situation where we can all talk, ask questions and solve it together. I opted for the open-ended version where we kind of solved it together. Afterwards there was about 10 minutes left for me to ask whatever questions I had.
The second round of interviews was basically the exact same as the first, just with different interviewers and different questions. The third round was with two more developers and was focused on architecture and system design. They mostly asked me to explain and discuss some things on my resume, and to diagram some of it on a virtual whiteboard.
Overall it was a very positive experience. I'm not great at solving whiteboard challenges, so I'm glad it was a "collaborative" effort. I believe they were still evaluating on my ability to think through things and my ability to work collaboratively with others, so it's not an automatic fail if you don't get it right. I little to no experience with system design, so the third interview was a struggle for me and that's where I failed out. If you have some good understanding about a few things you've done in that regard, that part would probably go better for you than it did for me.