I was asked to review this answer. I added a comment about how it could have been more helpful. And was then told, it was an inappropriate review.
Why is adding a comment considered to be inappropriate?
You got a Review Audit. On those, if the original edit was approved then you can only "pass" the audit by also clicking "looks okay". If you click anything else, including leaving a comment, you fail. It's dumb, but failing makes no difference unless you fail a lot...
This seems to happen once every few months, you're not alone.
Breaking it down: