That's the original use of AI: pattern recognition. Those are specialist systems, not at all like GPT. We've been benefiting from systems like this for a while: anti spam filters, image diagnostics are two common use cases.

I guess long term anemia leaves marks on the fingernails.

It's good that they're using it to screen for it then.

It's like the blood pressure screening you get every time you go to the doctor. It can't detect hypertension on its own, but can point you to the necessity for a test for it.

I imagine the end goal would be a machine that you put your fingers in and gives a chance of anemia present. That could be a screening for a proper anemia diagnosis.