Don't let the better-than-most perks blind you from the truth. There is an expectation to work long hours and if you don't you're seen as "not committed". While WFH was an option, you were monitored closely and micro managed. There's toxicity, favoritism and lack of empathy in some of the managers that put their own success above others. Very soon, you are undervalued and that's why the turnover is high.
