For some reason, on my Xbox, none of the farmer villagers in a nearby village would buy any of my pumpkins. I had about 43 in my inventory, but the trade slot was red, as if I didn't have any. The farmers were also not sold out of that trade. I then switched to my switch (no pun intended) and started farming, and then trading with my farmers there. After a while, the same thing happened. I'm not sure if I sold them out and they had raised the price, and that is when they stopped taking my pumpkins, even though I had a lot in my inventory, or something else. I'm not really sure how you could recreate this, apart from just trading pumpkins with farmers a lot. Both of these villages were in pains biomes. I can't get you a picture, because on my switch, I deleted the world.