Their website describes the process well. I had a few phone interviews (with maybe 1-2 technical questions per call), and then was flown to their HQ in Palo Alto. You sign an NDA when you walk in, so I'm not sure how specific I can get but, as their site says, there is a series of technical interviews lasting ~45 minutes each. My questions mostly related to data structures and algorithms. Some were easy, others were challenging, but they are doable if you don't give up and ask for hints when you need them.

Had a chat with HR and then a technical interview with an engineer. They gave some some quite normal leatcode type questions that I had to answer to continue to the next steps.