What are common failure modes you’ve seen for new engineers at Big Tech companies?

For me, the main way I've seen engineers fail at Meta is low code quality. You can tell they're not being very thoughtful in their code reviews and this reflects in the "dressing" of the code review as well (e.g. weak summary, test plan of just "it builds", etc).

At a higher level, I think what separates the SWEs between those at a Tier 1 company like Google and those at a Tier 2 or lower company is that the engineers at the top tier companies simply care. They weave depth into everything they do and strive to ship amazing software.