It may well be, but also Pangram is ridiculously transparent pseudoscience. Let's not play pretend that it's authoritative, please.
Edit: Just for fun I just defeated it with AI-generated text that it reported as 100% human-written. Great stuff. Truly genius scam.
It is not pseudoscience. Have you read about how it works?
I never found a piece of text that pangram claims is 100% AI that to me seems like purely human written text.
The only counter example is when a human composed a piece deliberately trying to mimic AI slop.
So call it an AI slop detector if you want, but either way it accurately identifies stuff I don't wan't to read.