Had a fairly good interview with the COO. Got rejected based solely on that.. I don't think a COO should be the first round of an interview process for any company, let alone a start up. Didn't ask me about any technical stuff really.. What made things worse was that they basically ghosted me until I reached out to the HR and asked for a update. I'm sure they're a "cool silicon valley startup", but these minor details often say a whole lot about a company.

I applied through an university job board. The interview process consisted of submitting some code for a small project (~2 hours work) and a video call. Questions asked related to basic machine learning, and a brainteaser for fun