I have personally seen this happen (ex-Amazon managers coming in and turning the place toxic) at 2 separate companies now

I've bumped into a lot of execs who say they don't want to hire ICs or managers (usually only one or the other) coming from specific big-name companies, and will instruct external and internal recruiters/HR and hiring managers about that.

Not big-name companies in general, but specific companies among them.

It seems to be about belief of culture taint risk (e.g., the way engineering is done, or the misaligned careerism or sharp-elbowedness that's promoted by the company). Though there's also sometimes a belief that particular large companies hire lots of people who aren't good (only, apparently, at LeetCode interviews).

I'm a bit sympathetic to those theories, though I personally don't rule out any individual. I think, say, all the FAANGs do also have individual people who are capable and well-intentioned, and haven't been permanently branded with whatever problematic culture of the company they're at.

(Though there was a time when I thought a person wouldn't have gone to one particular social media company unless they were either a sociopath or completely unaware of news in the real world, but it's more nuanced now. And there's currently an aggressively pro-fascism company that AFAICT never should've seemed like a good idea to anyone who wasn't evil or oblivious, though, I have to remember that they like to hire "impressionable children", and we now have tech track undergrads who haven't had time for anything but STEM classes and LeetCode since early teens, so they might be forgiven. I was recently considering denylisting anyone who'd gone to a different tech company, which had a well-known decades-long history of chronic underhandedness, but then I saw that a colleague who'd majorly helped me out once had finally gone there. Which is another lesson to myself not to generalize in ways unfair to the individual.)