Inconsistent results from dropping TNT minecarts at different altitudes

 picture of the results of dropping TNT minecarts from 100~1000 blocks above the ground is attached below.

As shown in the picture, the holes made from the TNT minecarts have a very inconsistent pattern, with some doing little to no effects.

It seems that the TNT minecarts would airblast when dropped from specific heights, which may have caused this issue, but I am not sure.