A three-step process with 8 interviews in total:
The first part was a screening, first with a sourcer, then with the hiring manager, with a possibility for the process to step after each discussion. Once those two steps were validated, you are proposed to move to a second step, which I would call the panel. Five interviews, one hour each, will evaluate you on people management, process management, product management, system design, and technical skills. You are supported by a recruiter throughout the process and are briefed on how to prepare best.
Once you have done that, all interviewers will debrief together and decide whether or not you go to the third step, which is a take-home assignment in which you are provided a vague description of some problems the Datadog org is facing and asked to propose solutions. Once you have analyzed the assignment and have prepared a proposal, you are invited to present it to a panel of interviewers (usually, the ones you have faced during the second phase).
The candidate who goes on top of this phase is then presented with an offer