I could be correct but way too slow in edge cases (unlikely with Rust but you never know), leaking temporary files, having security holes, etc.

There's much more about correctness of a piece of software than: "produces the same output as the original on x test cases".

I'm not saying it's a bad implementation and, if anything, LLMs are much better at translating/porting existing code (and finding bugs) than at writing things unheard of.

You're basically saying, if I may make a pun: "rust me bro, it's correct".