This doesn't spend much time on the scenario where it's not two peers in the review, but like a junior dev and senior dev.
I recently did a code review for someone who is very junior ^1^ , and after spending like two hours fixing all the syntax errors and low level goblins, I realized I couldn't see the forest at all. I'd been staring at the "this variable is undefined in this case" trees so much. And then they were getting antsy and management was getting antsy...
^1^ They're not actually junior. They've been in this role for years. Unfortunately, this org has like no mentorship and no standards, so they haven't actually learned much in all that time. They've just been copy-pasting code until stuff works.