That seems to make sense. Any suggestions to improve this skill of reviewing code?
I think especially a number of us more junior programmers lack in this regard, and don't see a clear way of improving this skill beyond just using LLMs more and learning with time?
You improve this skill by not using LLMs more and getting more experienced as a programmer yourself. Spotting problems during review comes from experience, from having learned the lessons, knowing the codebase and libraries used etc.
Find another developer and pair/work together on a project. It doesn't need to be serious, but you should organize it like it is. So, a breakdown of tasks needed to accomplish the goal first. And then many pull requests into the source that can be peer reviewed.
It's "easy". You just spend a couple of years reviewing PRs and working in a professional environment getting feedback from your peers and experience the consequences of code.
There is no shortcut unfortunately.