It's for compliance mostly. So whichever regulator sees that you have a code review checkpoint. I look for obvious things like tests with missing edge cases, copy pasta violations, and embarrassing things they missed.

If you have static code analysis, automated pipelines, and tests you shouldn't be stressed out about code reviews and they should be fast.

If I am on good terms with the dev and we have time (LOL) I might try to help them refactor something for clarity.