I'm not gonna make assumptions on behalf of OP, but if you have domain knowledge, you can quickly tell when a PR is vibe-coded. In a real world scenario, it would be pretty rare for someone to generate this much code in a single PR.

And if they did in fact spend 6 months painstakingly building it, it wouldn't hurt to break it down into multiple PRs. There is just so much room for error reviewing such a giant PR.