Flipsky 65220 with integrated esc issue

My 65220 20s5p battery diy efoil performs great at wide open throttle taking off ( medium setting on vx3) but when cruising speed 18 kph light throttle it has what feels like a stutter or micro cutouts in the motor.

Its audible and you can feel it

Best way to describe it is like a car with random engine misfire.

Any thoughts?