The web is full of independent observations of that exact fact, here's one that even comes with photos [1] but don't let me shatter your illusion. Feel free to keep giving them your money and supporting the enshittification.
"Are Moleskines fountain pen friendly? No. The paper quality is low in general, and fountain pen users will experience ghosting and bleedthrough that prevent you using both sides of the paper, and even some feathering on the front side. There are far better options available, and at a cheaper price."
"Are Moleskines fountain pen friendly? No. The paper quality is low in general, and fountain pen users will experience ghosting and bleedthrough that prevent you using both sides of the paper, and even some feathering on the front side. There are far better options available, and at a cheaper price."
[1] https://theanalogpastor.com/are-moleskines-fountain-pen-frie...