By "without preconceptions", I mean that your initial review should not be influenced by anyone else's opinions. In CS, conference management software often makes this explicit by requiring you to upload your review before you can see other reviews. (You can of course revise your review afterwards.)

You are also supposed to review the paper and not just check it for correctness. If the presentation is unclear, or if earlier sections mislead the reader before later sections clarify the situation, you are supposed to point that out. But if you have seen an AI summary of the paper before reading it, you can no longer do that part. (And if a summary helps to interpret the paper correctly, that summary should be a part of the paper.)

If you don't have sufficient expertise to review every aspect of the paper, you can always point that out in the review. Reading papers in unfamiliar fields is risky, because it's easy to misinterpret them. Each field has its own way of thinking that can only be learned by exposure. If you are not familiar with the way of thinking, you can read the words but fail to understand the message. If you work in a multidisciplinary field (such as bioinformatics), you often get daily reminders of that.