Well, the "accidentally making the S3 bucket public" scenario would be a good one. If you review carefully with full understanding of what e.g. all your policies are doing then great, no problem.
If you don't do that will you necessarily notice that you accidentally leaked customer data to the world?
The problem isn't the LLM it's assuming its output is correct just the same as assuming Stack Overflow answers are correct without verifying/understanding them.