Yeah, in most swe roles, you got some task from the PM that describe a new features. But you were not hired to just translate the ticket to code. More often, it’s your responsibility to figure out all those non-functional requirements, like don’t break anything that is currently working.

More often, the issue with legacy code is not that you don’t know how to make a change, it’s because you don’t know if and how it will blow up after making it.