Ah this makes so much sense!
I bought a book on Amazon Germany last year, 1000 Essays That Will Change The Way You Think, and as soon as I opened it I had a feeling it was a pirate copy. I even tried to find the book in a physical book store so I could compare, but didn't find it.
Just took it down from the shelf and went to the back page, and yes it's printed in Poland by Amazon Fulfillment.
I suspected it because the print looks weird, almost like a photocopy, uneven and thin and pale. The paper is like printer paper, and in general it just doesn't feel premium.
So the mystery is solved, but I feel cheated, even though the book was rubbish anyway.