You're totally right!

In my experience, the best way to detect AI is to analyze patterns, detect repetitive texts, extremely complex concepts without a source. If there are these types of patterns, and additionally the AI detector throws a high percentage, then it is probably an AI content.

Despite this, it is always difficult to be sure. As I said a few months ago, the best thing in these cases is to ask the authors for bibliographic references, so at least you make sure to stimulate real research and analysis (at least in many more cases)