A moleskine is an overpriced crap notebook at this point. Paper quality has drastically diminished from what it used to be, to the point where one can't use fountain or gel pens without bleed through. Another example of enshittification.
"from my own observations because I'm an expert in moleskins and I can tell you exactly why the paper quality has drastically diminished from what it used to be, here is the technique change"
or
"eh, I used a notepad once so I know what I'm talking about"
Because I'm quite sure I know a lot about moleskine, and I'm quite sure you are totally incorrect, a classic is 70gsm, there is no way it wouldn't reject a fp or gel.
Oh yeah, and as a note, I looked at your HN comment history, you might consider a once over of the guidelines, especially: "Please don't post shallow dismissals".
"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...