You may just have a keen level of self-awareness. If you don't have any suggestions, you can just say so. As you gain experience this will likely change, and

You may just have a keen level of self-awareness. If you don't have any suggestions, you can just say so. As you gain experience this will likely change, and you will have more to offer. Don't be fooled by your peers that look for superficial things to comment on. There are many people with the same amount of knowledge as you, but who are less self-aware and are adding noise the system, because they are scared of being perceived as incompetent. Find someone who has given you meaningful feedback during code/design review, and see what kind of comments they leave on other people's work. If you don't understand one of their suggestions ask them about it.