People working at Meta tend to gravitate around the same group of tech companies who offer the same range of salaries, same selection process, same internal structure. Many of them aren't particularly brillant SWEs (in the sense you don't need to be an elite coder or top PhD), although they can deliver based on the evaluation processes in these companies.

Meta has a bad reputation in some circles, but I don't think there's anything peculiar or particularly evil about them, at least not worse than similar publicly traded big tech companies. They are amoral money-making entities.

That being said I agree that their products suck. I don't use them, besides what's app because it's difficult to avoid. It's also end to end encrypted so it doesn't really matter regarding mass surveillance.