I was once told to stop wasting time submitting PRs adding null checks on data submitted via a public API. You know, the kind of checks that prevented said API from crashing if a part of payload was missing. I was told to stop again with my concerns dismissed when I pointed similar things out during code review. I left that company not long after, but it's still around with over a quarter of a billion in funding.

I would love to say that this was an exception during almost 20 years of my professional career, but it wasn't. It was certainly the worst, but also much closer to average experience than it should have been.