Player gets impulsed different height when combining impulse with another impulse without landing

Hello, I am developing for a game jam, I chose Exploding Barrels as my cliche`, But, if I make a barrel that impulses 100 on Z and then the player jumps onto an another barrel that was 200 on Z, the player barely jumps, but if I land in-between and separate them, then the player is launched higher Here is a video (I know the tutorial text is wrong, ignore it)

AddImpulse adds to the current velocity.

While on ground your Z velocity is 0, so when you hit a +200 barrel you get VelocityZ = 200.

When you hit barrel while falling down a part of the impulse is used to negate falling speed (eg: -50 + 200 = 150).

Solution is to cancel your current VelocityZ before adding impulse.