After a long interview process with 2 challenging coding problems and a lot of cultural / work experience questions I secured an offer. They gave a salary under both what I requested at the start and what was advertised on the job posting.
After asking if there was any possible flexibility in the salary, they ignored me for a week before replying with a patronising email about how I was not "all in from day one" - and since I didn't instantly accept the offer they would take it as a no. I have received no communication back since. This week long silence also meant that another offer I had received from another company expired as I never would have expected such a hostile response to asking about the salary. I was left with no offers.
Looking back there were a lot of red flags through the process but I was really excited about the product so ignored them. It doesn't seem that they want employees who advocate for themselves or know their worth, rather people who will do anything to work at such a "world changing" company. I don't expect they took my questions about work life balance well either. Only apply if you're comfortable with a culture that may not respond well to candidates questioning aspects of the offer or working conditions.