Really? Why? I thought FAANG jobs were the closest thing to heaven on earth.

Okay, I am being obnoxious, but seriously, this is first I have heard of this. Do you know why? Surely it can't be the remote work thing. I would assume there has to more to this.

It's the constraints that come from working in a large team/company - the bureaucracy, the politics, the kind of work (focusing more on scaling vs fun features). A lot more features can be tried out in a startup due to their smaller scale, but not if growth is the only thing they care about.

Have you ever worked for a large company? Some people thrive there, others would rather die.

I assume it's mostly about that.

Those people already left or are on their way out soon, and there is a fresh crop every year

There are still many who are coasting along because there is no better alternative.