> that ChatGPT can finish a leetcode problem before I've even fully parsed the question.

This is an interesting case for two reasons. One is that leetcode is for distilled elementary problems known in CS - given all CS papers or even blogs at disposal, you should be able to solve them all by pattern matching the solution. Real work is anything but that - the elementary problems have solutions in libraries, but everything in between is complicated and messy and requires handling the unexpected/underdefined cases. The second reason is that leetcode problems are fully specified in a concise description with an example and no outside parameters. Just spending the time to define your problem to that level for the LLM is likely getting you more than halfway to the solution. And that kind of detailed spec really takes time to create.