Google Scholar for certainly, here is turns up a huge number of academic papers that include parts that were evidently written by ChatGPT—sections that start with “Certainly, here is a concise summary of the provided sections:” are a dead giveaway.
Peer review isn’t built to handle the flood of AI content, especially as not all of it will be obvious, and not all will be malicious (lots of scholars pay editors to help make their writing better, now they will use chat).