Calling you out for lazy work. Teaching you how to use internal tools, company coding standards, suggesting better patterns, digging deep in to the context of system design and maintainability, suggesting other domain experts to tag in the reviews. I learned all sorts of Hack things that obviously I wouldn't learn outside from code reviews.
How are small things like "you left a commented out print/log" or "use color var not hex code" handled - or that a 'company coding standards' type thing. Are those types of things potentially automated with a linter or similar?