The Linux kernel gets a ton of PRs constantly. My big issue with LLM code is that it is really good at appearing to be thought out, but actually reverse engineering it can reveal major mistakes.

A good reviewer should still catch them, but it takes longer since the "code smell" is different. Humans will usually make consistent simple mistakes while LLMs will sometimes use advanced patterns to make the same mistake.

The fact that these take longer to review, are usually much longer in general, and are appearing at an incredible pace (1hr to generate, 1 day to review) creates a backlog that becomes unbearable to review.

A lot of open source projects have banned them for this reason, but the ones that do allow them tend to use LLM reviewers to help clear the backlog which is a whole different ouroboros of an issue.