Just a horrible company culture. There are a lot of buzz principles flying around like "selfless excellence" but in reality it's excellence in mediocrity and politics. Often startups preach a fail often and early strategy...ThoughtSpot does this with people. Sometimes as soon as 1 month in, talks are happening about letting go a new hire. Granted if this were an isolated case it could be about the employee, but with multiple people clearly something else is going on. Some good leaders left and some others were let go.
Beyond my personal opinion, just look at their actions. Recently the CEO did an interview on how to scale to a billion and he openly talked about replacing and changing out people for the different stages of growth...like he was talking about office furniture. Personal development and growth, or training weren't mentioned. Or just see how HR provides a stock answer on here to each negative review. It's ice cold.