Identifying potential bugs within a unit is only a part of a good code review; good code reviews also identify potential issues with broader system goals, readability, and idiomaticness, elegance and "taste" (e.g. pythonicity in Python) which require larger contexts than LLMs can currently muster.

So yes, the ability to identify a bug and providing a unit test to reproduce it is rather basic[1], compared to what a good code review can be.

1. An org I worked for had one such question for entry-level SWEs interviews in 3-parts: What's wrong with this code? Design test cases for it. Write the correct version (and check if the tests pass)