Every crop besides pumpkins (maybe melons, haven't tested) yields the same number of its seeds as to when you break it with your fist aswell as when you break the soil underneath. With pumpkins, I found that you more often get seeds from breaking the stems rather than breaking the soil beneath, while this number should be the same. I know that pumpkin seeds don't always drop from breaking the stems, but out of a plot of soil, I had better luck with breaking the stems with my fist than I did breaking the soil. I know this is a small bug, but for consistency purposes, I figured I might as well report it in hopes that this is patched in 1.14.2 or any future releases (since it's obviously not a priority, but also shouldn't be hard to fix).