The process is very, very time consuming and you might be rejected due to minor subjective perceptions of one single interviewer. The compensation they offer is similar or even slightly below other offers I cleared in Madrid. Also you will most likely not work on the core observability product but on other experiments they are doing. For one of the teams I interviewed for, I would seriously question the product market fit of what they are doing. So think carefully if it is really worth it.
The interviews are late in the evening / night due to the hiring team being located in another timezone. You really only get the result after going through the entire process. The process in Detail:
1. Call with Recruiter
2. Call with Hiring Manager
3. In-depth presentation of a past project - prepare presentation beforehand
4. Architecture Design
5. Delivery and Project Management
6. People Management and Leadership
7. Life Coding (Leetcode-Level Easy-Medium)
All but the first call take one hour. That is a total of 6.5 hours plus a lot of preparation. I managed to clear all rounds except 6. and was just rejected because a manager several levels above the actual role and who never really would have worked with me found that my description of interaction with the team lacked some detail.