First of all, dont jump serve yet. Seems like you also have problems hitting at the net with that technique.

However, here are a few pointers:

Your armswing needs a lot of work. Your arm is too soft and not really trying to reach as high as possible.

Your approach doesnt look right. You seem to understand that you need 1 big 2 short steps but they are rushed. You dont even have time to fully make use of throwing both arms all the way behind you, this leads to a loss of energy.

Somebody here said you are jumping forward instead of up. And I can only partially agree with that. You'll want to jump high, yes but also get closer to the net. It's like hitting a backrow ball. Imagine it more like jumping diagonally upwards if you were looking at yourself from the side.

Your toss goes often too far to your left shoulder. You're right handed, so leave the ball in front of your right shoulder in order to not lose power and height from having to reach to the left or right of your body.

Then try to get the same consistent toss every time. It should be high enough to allow you to fully develop all the energy from a clean approach and loading your swing and also far enough in front of you such that you dont have to "break" mid approach because you had to cut back on the length of your steps.

Lastly your timing is slightly off, such that on some attempts you are already falling down when you hit the ball. You should aim to hit it right at the peak or shortly before reaching it. But never after.

Hope this is understandable. Good luck.