It means you can read and understand the instructions on a pack of ramen but can’t pick up on nuances, infer bias or apply any kind of abstract reasoning to a piece of text

Question what is considered 6th grade.

This is a statement, telling the reader to consider, or be skeptical of, what the common understanding of what 6th grade is.

Question: what is considered 6th grade?

This asking the reader what most people think 6th grade is.

So, how did you read the comment? It isn’t a question; it’s a statement in both sense of the word.