Answer:
It is due to 2 reason:
When you free fall, there are 3 stages possible: the upward phase, in which you gain acceleration
The stop phase, when acceleration is 0, and it can either occur as a stop in a pick point (the moment you or the object stop going up but yet to go down)
And the decreasing acceleration due to air friction which is not neglected in this question.
Mostly, when you throw objects upwards, they go through all 3 phases, and then it would be confusing
When you skydive, you go through phase 2&3. You also reach terminal velocity in which acceleration is 0 and speed is constant
Here you have a skydiving situation though it is more confusing due to the circumstances
The speed will increase, but the initial acceleration will be 9.8 and will decrease (even though very little) due to air friction
Acceleration during free falls is either constant or decreasing
The only way for it to increase is by a non-gravitational force that will drive the object outwards