The issue is they placed 2 speed bumps that size right behind each other, without enough spacing.
So you go over the first speed bump and while your car suspension isnt settled and while on the rebound your already hitting the second bump. When that happens, your car is rebounding(going up) as it goes up the second speed bump, so it amplifies the affects like you're going off a ramp.
Thats why they launch so high off the second one. This is the cities fault.