The problem is that you need to actually do training to detect AI text, and no one wants to spend money on that. The actual implementation is very easy:
1. get a corpus of real text
2. generate a corpus of AI text
3. train a model until it can tell the difference
The problem is step 2 is semi-expensive and step 3 is really expensive, so everyone is trying to shortcut the process, and of course it doesn't work.
There are many out there but I don't know about the "latest". GPT-4 itself says it has only a 10% chance of having been generated by a LLM.
These detectors are really unreliable. I've fed them content that I generated from GPT-4 and they never detect it as AI-generated.
I pity the students whose teachers will use them to detect plagiarism.