Well, turns out that 3 of the APIs changed the way they return the data, so instead of separating the logic, someone kept adding a bunch of if statements into a single function in order to avoid repeating the code in multiple places. It was a nightmare to maintain and I ended up completely refactoring it, and even tho some of the code was repeated, it was much easier to maintain and accommodate to the API changes.

The code quality was much better than in my current workplace where the reviews are done in minutes, although the software was also orders of magnitude more complex.

No amount of unit/integration tests cover every single use case in sufficiently complex software, so you cannot rely on that alone.

I remember having to do such a code review before an AI in a highly complex component, and it would take a full day of work to do it. In this day and age, most of the people i know take like half an hour and are mostly scanning for obvious mistakes, where the bigger problem are those sneaky non obvious ones.