That's a base salary of $136,750 plus stock and bonus. It's a middle-class salary given the high cost of living in the region[1] and the competition for talent. It's also not at all out of line with what investment banks and white-shoe law firms pay their associates.
Meanwhile, I believe younger talent is underpaid across the board in industry. In many cases junior employees make less than half what their more experienced colleagues do, even though the juniors tend to take on more than their fair share of the workload, and they often are relegated to doing the tasks and projects that the seniors don't want.
I think this is mostly based on ingrained beliefs in dues-paying and hazing culture (tendency for existing members of an in-group to exploit the newest members) rather than any empirical measure showing that juniors are that much less valuable from a productivity standpoint.
[1]It's estimated that you need to make north of $200k a year to be able to afford to buy a single-family home in the SF area: https://sf.curbed.com/2019/3/25/18277602/income-buy-home-san...