Like I said in another thread.
Onions are complicated.
Yes they thought they went through two years in one and set seeds.
Onions will bolt when they get I think about 5 to 7 leaves on them if they think it is the second year or it is the second year.
If they think it is the first year then you want as many leaves on them as you can get.
13 to 14 will make a good size onion.
Each leaf is a layer of onion.
Chopping leaves to the ground and stomping over said leaves will not make a bigger bulb.