Collective[i]'s interview experience is a classic LinkedIn/Reddit story. They initially promised a quick 2 week interview process, but kept sending false signals and adding stages baiting with "the next step will be an offer" for a 7 stage 1+ month process with a project in the end. The only reason why I played along was to practice my interview skills despite I made very reasonable guesses they probably weren't hiring.
They actually gave me a verbal offer at the final interview (which I obviously did not believe, so I didn't hold my breath) and a week later I got a rejection saying they "hired somebody else". It's been 5 months and the job posting is still on their website, so they are likely "evergreening" to their investors.
It's not a bad place to practice your interview skills, since you are going to meet some very smart people that will make you think. But they are definitely not hiring and last I checked, they just laid off 80% of their workforce according to some of their employees.